Usenet Newsgroups are the Ultimate Bulletin Boards. If it exists on the Internet, you can find it on Usenet. Anything from support to warez. Pictures of horses? Got that. Pictures of horses and bunnies? They probably have a group *dedicated* to it. The main use, tho is either warez\porn or support for... well... ANYTHING, cars, computers, horses.
I will advise caution for new users. If you are hunting warez, just like the P2P networks, make sure you have a good virus scanner ready. If grabbing porn, there are times when you think you are getting one thing, but you get another. Sometimes illegal other stuff. Be careful.
Oh, and search the Hot Deals forum for a large hard drive deal. You'll need it.