I have never come across one. To be honest, they would be worthless anyway as you can only download 5GB per day on a premium account. Any accounts in the public domain would be sucked dry within seconds of 00:00 every day.
I don't mind paying for it, fairly cheap considering the speed they give and ease of use.
Get a couple of mates in on an account and it won't cost more than a pint anyway! I shared an account with two mates and we never had any warnings or blocks put through despite what the rules say. The downside is that you are now limited to 5GB a day so you will have to come to an agreement between you about who can download when etc...