Here (courtesy of CNN) are the results of the last two elections.
In 2004, Kerry lost by 34 electoral college votes with just 3 states changing hands from the 2000 election - New Hampshire moving to the Democrats while New Mexico and Iowa moving to the Republicans.
With the polling as it is, it seems very likely that Obama will win all the states that Kerry won for the Democrats in 2000. If he does this, then it's going to take very little to move the number of electoral college votes in Obama's favour. For instance, if Florida moves Democrat then one state alone will mean a swing of 54 votes to Obama and the election will be won.
But it's just not Florida that happens with. If Obama wins Ohio for the Democrats, that would be a swing of 40 votes and a victory. If Obama manages to take back New Mexico's 5 votes, then he would just need North Carolina's 15 votes for a swing of 40 votes and a victory. If Obama manages to take back both New Mexico and Iowa that would be 12 more votes and mean winning just about any other red state will, once again, give him victory.
Given the results from the previous two very tight elections together with the current national and battleground state polling, it is very difficult to see the electoral maths being anything other than very favourable to Obama. It is hard to see McCain being on the offensive in any Democratic state right now, leaving him having to struggle to defend every Republican state to get a victory. I just can't see him doing that.
Obama will win tomorrow night, the only question for me that remains is just how large will his margin of victory be?