I take 5-htp after rolling and I've found it helps a lot. I actually take it during times of regular life stress too when I have trouble sleeping (1 12hr release tab right before bed and I sleep like a baby and wake up in a great mood.) Or I take it when I'm PMSing and notice that my grumpy attitude is non-existent.
Some people say it doesn't work for them, some day it does, so try it and see if it's right for you. I've found it for cheap at Costco (about $20 for 300 tablets.)
Also note that you should NOT take it 24 hours before you roll. Some say that it can decrease your roll greatly.
@levictus - I've never heard of Piracetam, but that sounds great!