A popular narrative from the first McCain-Obama debate was that Obama spent the whole night agreeing with his opponent. MSNBC's Chris Matthews particularly obsessed on this point and his network illustrated the thought with a montage of Obama repeatedly saying "John is right about ..."
What's been lost in this analysis is how Obama used his me-too-ism as a debating tactic. True, at times his point was simply to concur with McCain (and probably present himself as gracious, bipartisan, and presidential). But on at least a few occasions, he agreed with McCain as a means of turning the GOP nominee's own words against him.
These are the two examples that jump out: After McCain dismissed Obama's foreign-policy ideas as naive and dangerous, Obama said "John is right that a president has to be prudent." Obama then followed by noting that publicly threatening the extinction of North Korea and singing songs about bombing Iran don't give McCain much credibility on the issue. Earlier in the debate, when McCain attacked Obama on earmarks, Obama agreed that earmarks were a concern but said they amounted to $18 billion a year (that figure itself is much debated) and suggested that if McCain was so concerned about losing that much revenue, he should be much more alarmed about losing $300 billion, the price-tag Obama put on McCain's tax-cut proposal.