If you haven't heard of it, bitvegas is a minecraft bitcoin casino. Every few minutes you can exchange a "free gift" for .5 mBTC. You start the server with around 20 of these, but I have 1800. I don't want to spend the time to withdraw them all so if you want to give me 0.3 Bitcoins, I will let you use my Minecraft account until you get all my free gifts.

This is a guaranteed 300% return if you're willing to take the time to redeem the gifts.