Bitcoin. I would have preferred to trade on margin instead of locking up my credit cards, but they wouldn't give me a margin account yet and I really wanted to get in before this thing took off.

It's definitely more risky, but I think it's worth it. And, I'm young enough that I can afford to take the risk. I'm not quite 40 yet, otherwise I may feel different about this. I am a little worried that the price has dropped almost $400 since I've bought, but I'm in this for the long run so I'm not gonna worry about the 4000-ish dollars that I've lost so far (on paper only).