I checked out some others from a link someone else provided. It seems like they get you with the auto renewal of the contract. Many contracts are a fixed price for the life of the contract, then variable pricing after the initial contract expires. So, if you have a 9 month contract at $.16/kwh, once the 9 months is up, they can charge you anything and change whenever they want.

I might still look into this, but I'll be calling them and having them send me a copy of the contract before signing up. I'd want to know how far in advance I have to say I don't want to renew, so I know if I'll end up screwed or not.