Off-shore drilling.
One example is enough to prove you wrong, and I'm too tired to list all the others.
Obama didn't flip-flop on offshore drilling, he said he's open to it as a last resort in a comprehensive energy plan.
Let's take a look at some of John McCain's flip-flops:
offshore drilling
iraq
tax cuts
social security
political reform
immigration
gay marriage
negotiating with Kim Jong Il not acceptable, until Bush did it..
negotiating with Fidel Castro
the estate tax
MLK day
teaching alternatives to evolution in school