Try modafinil/provigil. My friend takes it for his narcolepsy and says it works great with no real side effects as of yet. He's gone for 7 days on only 6 hours of sleep at one time. Ive been wanting to try some for awhile but he can't spare any b/c his narcolepsy is rather severe.
http://www.modafinil.com/ has some good info on the pills.