I'm a big fan of Usenet but it has a small learning curve as well as monthly subscription fee - it's probably still the biggest grey area/best kept non-secret secret on the net. Viva la Newsleecher.

Not to totally geek this thread out but I have a buddy that works in a NOC at a cable ISP and the job of weeding out torrent kiddies and other 'undesirables' just got a whole lot easier after they got the system in this demo - check it out in case you want to see what ISP's are using to watch your ass:

http://www.proceranetworks.com/procera_demo_video.html