Progress for America
American Future Fund
Freedom's Watch
American Future Fund
Freedom's Watch
They also list MoveOn and several other liberal 527's. But several of the progressive groups have said they will not engage in smear campaigns because of Obama's request to refrain from such bullshittery. The Rethuglicans..not so much.
Also, Obama has started up a site to fight all the smears rearing their ugly heads already..like the Michelle Obama "Whitey" tape that doesn't exist and several other specious lies. Your can reach it by typing www.fightthesmears.com.