Go pills (ie No-Doz). Same thing I use to stay awake in class sometimes. I don't drink coffee, so it's pretty much either that or fall asleep. Alex
No pills here ... Mountain Dew and sunflower seeds do the trick for me. For some reason, Jolt doesn't really do anything buzz-wise for me.
Windows down, good music (hell, even oldies that you sing to), and a beverage. That and try to keep the mind active. That has helped me plenty of times driving from Colorado to the midwest.
Loud music or singing just about anything will do it. Snickers bar or some sort of sugar, or on occasion; yelling as loud as I can.