He's unerring in knowing what the public will pay attention to, he's ruined people's lives, and Bush won't make a move without him, he's Karl Rove! Never mind trying to tar the war president, focus on this guy. Nothing in particular, just talk about him a lot, make sure people know who he is, even off the internets. The key here is shining enough daylight on someone who's public presence is miniscule in comparison to his actual power. Back in Texas, Bush often resented people talking directly to Rove, so maybe you can even drive a wedge between them-- just don't let any mention of Bush or presidential news go without questioning how Rove is involved. Ideally, a viral sticker campaign on the lines of the Andre the Giant Has a Posse phenomenon would be good-- something that captures simply and quickly the essence of the powerbroker mastermind and gets people talking. He's got his tendrils wound through all levels of government and the political machine, so if you can pull him out, the beast will fall.

For something more insightful and useful on a grass roots level, Matt Fraction has been talking about the organizational problems he found while volunteering during the election season. Really good points within, check it out.