I took modafinil twice. I'd been having problems staying awake during the day -- it's hard for me to sleep before 2am -- and those completely disappeared. I had more energy then than I've had in a while. No negatives. The only reason I haven't gotten more is that I don't have a mailing address.

(Disclaimer: I drink a lot of coffee and tea, use a lot of snus, and drink like a relevant ethnic stereotype on weekends.)