There is a service I found on Freenet that said he'd double my bitcoin in 24hr.  I tried him out with .05BTC and he sent back .1BTC.  Anyone else ever used him?  For those without freenet, this was basically his website:

Send any amount of Bitcoins 0.01min 5BTC max to 1EDibafVUYe9D34J5hnVo1nZmVZggveH9r
and we'll send back double in 24 hours.

Worked for me...