We are in full swing now in the presidential campaign, and we are constantly bombarded with poll numbers. Funny thing is, most of those polls are just national polls, a prediction of how the nation-wide popular vote will turn out. But as the 2000 election underscored, that doesn't matter at all: what matters is the electoral vote. To predict that, you'd have to track individual state-by-state polls to see who wins the popular vote in each state, and compute the electoral vote totals. Sounds like a lot of work, but FiveThirtyEight.com (Electoral Predictions Done Right) has done all the work already. They also run statistical simulations to predict the likelihood of various outcomes (for example: the chance of McCain losing the popular vote but winning the election is 1.7%).
Add extensive tables of data detailing the poll data, the simulations, their predictions, maps of outcomes, more of the same for congressional races, and so on, and you have a quantitative political junkie's dream site.
BTW, as of this moment, they predict an Obama win, with 339 electoral votes to McCain's 199.