100% sure way to game the appstore!
I was just sent an unsolicited email from a firm offering to help me buy my way onto top lists. They have a service where a developer can pay them to have people buy your app en-mass and post fake user reviews. I won't mention this company by name, but I was a bit taken aback. I'm not surprised that this sort of thing goes on, but I'd assumed that discussions with PR firms that do this sort of thing always happened behind closed doors. To have a company come out in the open offering this type of transaction without any pretenses of being legitimate is pretty shocking.