For those of you interested in national politics, you might want to take a look at http://www.electoral-vote.com. During the 2004 election, it provided a semi-weekly update of state-by-state tracking polls, showing who was winning each state. (Overall, it was as accurate as the polls were, or weren't.) This time around, the site is tracking all of the active Senate races.
Trivia: the site is being run by Andrew Tanenbaum, a noted and respected computer scientist, who happens to be an American living abroad.