Congressional Quarterly has an interactive map that lets you see how Obama and McCain did by congressional district. You can see, for instance, that McCain won West Virginia's 3rd Congressional District 56-42%, even as Democratic congressguy Nich Rahall carried the district with 67% of the vote. Or that B. Obama won New York's 23rd by 5% while Republican representative John McHugh skated by Democrat M. Oot by more than 30 points in the same district.
The map looks redder than you might expect, but that's due to the fact that - to quote Wee Willie Keeler, who said it in a different context - the Republicans tend to "hit 'em where they ain't"; they do better in the parts of the country where people tend not to live, and where the congressional districts eat up more of the map. In fact, Obama won 242 of the 435 districts in the country (though he actually underperformed congressional Democrats, who won 257 districts).
Meanwhile, Beyond Chron notices that Republicans in California, already a threatened species, may need to claim full endangered status in the near future:
Barack Obama carried eight Congressional Districts that had long voted for Republican presidential candidates, and John McCain came close to losing three more. All these districts are currently represented in Congress by Republicans, but a few incumbents came close last year to losing to Democratic challengers. It’s only a matter of time before some of these districts will eventually flip. None of this is a surprise, however, because the state’s Republican base is older, whiter and shrinking in size.Old, white, and shrinking. Forget politics - I don't think anything that can be described that way is in good shape.