1-Share the stuff from www.magnetmix.com. Those folks who posted their stuff there are taking a chance on legitimate content via p2p, so support them by helping spread out the bandwidth.

2-setup so you run as an Ultrapeer. On a good connection, you can contribute about 1 GB/24 hrs of bandwidth--relaying searches, acting as a middleman between two firewalled hosts, and all the other kinds of jobs needed to keep the network healthy. That's a pretty decent contribution alone.

3-hunt up legitimate content that you think others would like, like indie music, and help share it. The movie /music industry controls the publicity, but you can control the content on the network. Search for posts by topbanana to see some of the collections he has put together. They may not be as popular as fake-named files, but there's usually pretty regular requests for his collections.

IOW--there's lots you can do without giving your bandwidth to the music/movie industry popularizing their content.

Cheers