Here's what I've found in various places around the "Internets."  If there are more, or new, instances, feel free to add them in the comments.
* McCain supported the drilling moratorium; now he’s against it.http://www.washingtonpost.com/wp-dyn/content/article/20... 
* McCain strongly opposes a windfall-tax on oil company profits. Three weeks earlier, he was perfectly comfortable with the idea.http://www.huffingtonpost.com/2008/06/18/mccains-offsho... 
* McCain thought Bush’s warrantless-wiretap program circumvented the law; now he believes the opposite.http://www.thecarpetbaggerreport.com/archives/15781.htm... * McCain defended “privatizing” Social Security. Now he says he’s against privatization (though he actually still supports it.)
http://www.thecarpetbaggerreport.com/archives/15863.htm... * McCain wanted to change the Republican Party platform to protect abortion rights in cases of rape and incest. Now he doesn’t.
http://www.huffingtonpost.com/2008/05/10/mccain-flips-o... 
* McCain thought the estate tax was perfectly fair. Now he believes the opposite.http://www.thecarpetbaggerreport.com/archives/15825.htm... * He opposed indefinite detention of terrorist suspects. When the Supreme Court reached the same conclusion,he called it “one of the worst decisions in the history of this country.”
http://www.thecarpetbaggerreport.com/archives/15864.htm... * McCain said he would “not impose a litmus test on any nominee.” He used to promise the opposite.
http://www.americablog.com/2008/06/now-mccain-is-flip-f... 
* McCain believes the telecoms should be forced to explain their role in the administration’s warrantless surveillance program as a condition for retroactive immunity. He used to believe the opposite.http://www.washingtonpost.com/wp-dyn/content/article/20... 
* McCain supported storing spent nuclear fuel at Yucca Mountain in Nevada. Now he believes the opposite.http://www.lasvegassun.com/news/2008/may/28/mccains-abo... /
* McCain supported moving “toward normalization of relations” with Cuba. Now he believes the opposite.http://www.thecarpetbaggerreport.com/archives/15617.htm... * McCain believed the U.S. should engage in diplomacy with Hamas. Now he believes the opposite.
http://www.thecarpetbaggerreport.com/archives/15557.htm... * McCain believed the U.S. should engage in diplomacy with Syria. Now he believes the opposite.
http://www.thecarpetbaggerreport.com/archives/15564.htm... 
* McCain supported his own lobbying-reform legislation from 1997. Now he doesn’t.
http://www.huffingtonpost.com/2008/05/20/mccains-97-lob... 
* He wanted political support from radical televangelists like John Hagee and Rod Parsley. Now he doesn’t.http://www.thecarpetbaggerreport.com/archives/15633.htm... * McCain supported the Lieberman/Warner legislation to combat global warming. Now he doesn’t.
http://www.thecarpetbaggerreport.com/archives/15699.htm... *McCain pledged in February 2008 that he would not, under any circumstances, raise taxes. Specifically, McCain was asked if he is a“‘read my lips’ candidate, no new taxes, no matter what?” referring to George H.W. Bush’s 1988 pledge. “No new taxes,” McCain responded.Two weeks later, McCain said, “I’m not making a ‘read my lips’ statement, in that I will not raise taxes.”
http://www.thecarpetbaggerreport.com/archives/14761.htm... * McCain is both for and against a “rogue state rollback” as a focus of his foreign policy vision.
http://blogs.abcnews.com/politicalradar/2008/04/mccain-... 
* McCain says he considered and did not consider joining John Kerry’s Democratic ticket in 2004.http://www.thecarpetbaggerreport.com/archives/14818.htm... *In 1998, he championed raising cigarette taxes to fund programs to cut underage smoking, insisting that it would prevent illnesses and provide resources for public health programs. Now, McCain opposes a $0.61-per-pack tax increase, won’t commit to supporting a regulation bill he’s co-sponsoring, and has hired Philip Morris’ former lobbyist as his senior campaign adviser.
http://www.thecarpetbaggerreport.com/archives/15033.htm... * McCain has changed his economic worldview on multiple occasions.
http://www.thecarpetbaggerreport.com/archives/15337.htm... * McCain has changed his mind about a long-term U.S. military presence in Iraq on multiple occasions.
http://www.thecarpetbaggerreport.com/archives/15370.htm... * McCain is both for and against attacking Barack Obama over his former pastor at his former church.
http://www.thecarpetbaggerreport.com/archives/15358.htm... * McCain believes Americans are both better and worse off than they were before Bush took office.
http://thinkprogress.org/2008/04/19/mccain-economy-bloo... /
* McCain is both for and against earmarks for Arizona.http://thinkprogress.org/2008/01/06/mccain-earmark /

*McCain’s first mortgage plan was premised on the notion that homeowners facing foreclosure shouldn’t be “rewarded” for acting“irresponsibly.”His second mortgage plan took largely the opposite position.http://www.thecarpetbaggerreport.com/archives/15176.htm... * McCain vowed, if elected, to balance the federal budget by the end of his first term. Soon after, he decided he would no longer even try to reach that goal.
http://www.nytimes.com/2008/04/16/us/politics/16mccain.... * In February 2008, McCain reversed course on prohibiting waterboarding.
http://www.huffingtonpost.com/2008/04/10/emtimeem-has-m... 
* McCain used to champion the Law of the Sea convention, even volunteering to testify on the treaty’s behalf before a Senate committee. Now he opposes it.http://www.washingtontimes.com/news/2007/oct/31/mccain-... /
* McCain was a co-sponsor of the DREAM Act, which would grant legal status to illegal immigrants’ kids who graduate from high school. Now he’s against it.http://www.washingtontimes.com/news/2007/oct/31/mccain-... /
* On immigration policy in general, McCain announced in February 2008 that he would vote against his own legislation.http://www.thecarpetbaggerreport.com/archives/14447.htm... *In 2006, McCain sponsored legislation to require grassroots lobbying coalitions to reveal their financial donors. In 2007, after receiving“feedback” on the proposal, McCain told far-right activist groups that he opposes his own measure.
http://www.thecarpetbaggerreport.com/archives/9658.html * McCain said before the war in Iraq, “We will win this conflict. We will win it easily.” Four years later, McCain said he knew all along that the war in Iraq war was “probably going to be long and hard and tough.”
http://electioncentral.tpmcafe.com/blog/electioncentral... *McCain said he was the “greatest critic” of Rumsfeld’s failed Iraq policy. In December 2003, McCain praised the same strategy as“a mission accomplished.” In March 2004, he said, “I’m confident we’re on the right course.”In December 2005, he said, “Overall, I think a year from now, we will have made a fair amount of progress if we stay the course.”
http://thinkprogress.org/2007/08/18/mccain-greatest-cri... /
* McCain went from saying he would not support repeal of Roe v. Wade http://mediamatters.org/items/200610310003 to saying the exact opposite.http://thinkprogress.org/2006/11/19/mccain-abortion /
* McCain went from saying gay marriage should be allowed, to saying gay marriage shouldn’t be allowed.http://www.vanityfair.com/politics/features/2007/02/mcc... * McCain criticized TV preacher Jerry Falwell as “an agent of intolerance” in 2002, but then decided to cozy up to the man who said Americans “deserved” the 9/11 attacks.
http://www.thecarpetbaggerreport.com/archives/6988.html * McCain used to oppose Bush’s tax cuts for the very wealthy, but he reversed course in February.
http://www.thecarpetbaggerreport.com/archives/6731.html * On a related note, he said 2005 that he opposed the tax cuts because they were “too tilted to the wealthy.” By 2007, he denied ever having said this, and insisted he opposed the cuts because of increased government spending.
http://www.nytimes.com/2008/03/03/us/politics/03mccain.... *In 2000, McCain accused Texas businessmen Sam and Charles Wyly of being corrupt, spending “dirty money” to help finance Bush’s presidential campaign. McCain not only filed a complaint against the Wylys for allegedly violating campaign finance law, he also lashed out at them publicly. In April, McCain reached out to the Wylys for support.
http://abcnews.go.com/Politics/story?id=1880630&page=1 
* McCain supported a major campaign-finance reform measure that bore his name. In June 2007, he abandoned his own legislation.http://www.nysun.com/national/campaign-finance-effort-r... /
* McCain opposed a holiday to honor Martin Luther King, Jr., before he supported it.http://news.yahoo.com/s/usnw/20070115/pl_usnw/dnc__mcca... * McCain was against presidential candidates campaigning at Bob Jones University before he was for it.
http://www.thecarpetbaggerreport.com/archives/8313.html * McCain was anti-ethanol. Now he’s pro-ethanol.
http://www.msnbc.msn.com/id/15637887 /
* McCain was both for and against state promotion of the Confederate flag.http://mediamatters.org/items/200610310003 * McCain decided in 2000 that he didn’t want anything to do with former Secretary of State Henry Kissinger, believing he “would taint the image of the‘Straight Talk Express.’” Kissinger is now the Honorary Co-Chair for his presidential campaign in New York.
http://thinkprogress.org/2006/12/19/mccain-kissinger /
* McCain used to think that Grover Norquist was a crook and acorrupt shill for dictators. Then McCain got serious about running for president and began to reconcile with Norquist.http://thinkprogress.org/2006/12/19/mccain-kissinger /
* McCain took a firm line in opposition to torture, and then caved to White House demands.http://www.washingtonmonthly.com/archives/individual/20... * McCain gave up on his signature policy issue, campaign-finance reform, and won’t back the same provision he sponsored just a couple of years ago.
http://www.thecarpetbaggerreport.com/archives/8066.html 

* In 2006, McCain sponsored legislation to require grassroots lobbying coalitions to reveal their financial donors. In 2007, after receiving “feedback” on the proposal, McCain told far-right activist groups that he opposes his own measure.