Optimum Nutrition has a product called Amino Energy, its basically aminos an caffeine, so its a nice little 2 in 1 if you like pre-workouts. Plus its nice because it doesn't have all that other crap that pre-workouts normally have. It's just green tea extract and green coffee extract.
My energy in the gym and the rest of the day after I'm done with the gym is increased when I'm taking aminos, if I don't take aminos I feel way depleted for the rest of the day after my workout.