The simExchange site is pretty cool.
If anyone is participating there it looks like there is some oppurtunity to on the PS3 futures for April NPD. The "market" is currently predicting 148K PS3's, while March's numbers were only 130K for a 5 week month and vgcharts new weekly's are showing PS3 slipping below 20K/week. 20K x 4 ~ 80K.
Anyway, it's a pretty fun way to see how your predictions turn out.







