Another list, this time looking at GOP House incumbents in districts where Barack Obama can be expected to do well.
Again, races that have already made the punditocracy's radar are in bold:
At the top of this list, outside of the Miami districts, are frequent targets like Chris Shays, Mark Kirk, Dave Reichert, Jim Gerlach, etc. Some of the Northeastern Members (LoBiondo, King, Castle), have somewhat pro-labor records and are probably safe. But outside the top 10 there are several districts that aren't on anyone's radar. For example Obama stands a chance at winning Mike Rogers district in MI-08 (Lansing, exurban Detroit), but Rogers is in the conservative half of the Republican Caucus. He should have a substantial challenger, but he doesn't. Here's the website of his opponent, Bob Alexander (D).
If we draw the line at districts where Obama gets 45% of the vote, there are 58 vulnerable incumbents and 14 vulnerable open seats. Not all of those will pan out, but it shows that the potential field is very large.