$100 to $200

[Ankesh]

Because things have been a bit slow at sowpub - a question to help spark a few good discussions...

What would you do to turn $100 into $200 in the shortest time possible?

(Or even better - what have you done in the past to turn $100 into $200 within a day or 2?)

Conditions of answering the question:
* The idea should be entrepreneurial in nature. No get a job that pays $20 an hour.
* Lets discuss ideas that actually requires spending $100 if we can.
* Hopefully, your idea can be implemented by others with ease too. And doesn't require a lot of specialized knowledge / expertise.
* A couple of people will answer "chattel." If you do - please suggest what to buy for $100 that could be sold for $200... and give details.