Beta alanine has had some good results in the literature; I've heard of a lot of lifters swear by it too. I tried it out and the tingling side-effect definitely makes for a good work out (which is why it gets added to almost all pre-workout formulas).
I usually get some whey, maybe mixed with maltodextrin, as well. That's just more of a nutritional choice but I feel fueled during my workout.
Caffeine is probably the best though. If you don't like coffee (like myself), you can buy it as pills too.