...here's a list of the 2008 US presidential candidates:

And their respective runningmates:

There's actually a lot of other candidates, but the ones posted here are those that actually have a legitimate chance of winning the Presidency. And by legitimate, I mean that they have ballot access in a sufficient number of states (including D.C.) to actually win the election, as shown below:

BALLOT ACCESS:
Obama/Biden - 51 states (538 possible electoral votes)
McCain/Palin - 51 states (538 p.e.v.)
Nader/Gonzalez - 46 states + 4 "write-in" states (456-531 p.e.v.)
Barr/Root - 45 states + 2 "write-in" states (503-510 p.e.v.)
Baldwin/Castle - 37 states + 12 "write-in" states (318-516 p.e.v.)
McKinney/Clemente - 32 states + 17 "write-in" states (368-528 p.e.v.)
Moore/Alexander - 8 states + 30 "write-in" states (102-338 p.e.v.)

If you're going third-party, check if your state has declared your pick as a registered candidate. If you're voting Republican or Democrat, then you don't have much to worry.

So Americans, I beg of you, PLEASE VOTE WISELY. Because it's not just your future that's at stake. The whole world's future lies in your hands as well. Use your mind and your conscience.