HDcavern — Don't ever use these guys - they're a scam.
I got sucked into this through HDcavern.com, which said that if I signed up for one offer that I would be able to make $50 that same day. Well, I signed up for two months' trial, and cannot cancel it through them. However, for that "free" trial they already took a dollar out of my account and I have no idea why. Don't ever use these guys - they're a scam.