Buy the latest Computer Music (August) and you'll get Guitar Rig LE on the DVD for free! I looked inside the mag and the LE is surprisingly loaded with what I personally consider essentials (compressor, overdrive, distortion, chorus, and others). I have the full version, myself, but I think I'd probably be plenty happy with just the LE. The mag's only $15. It may be one of the best freebies they've ever had.

Two other sites I don't think were mentioned that you might want to check out:

http://www.acmebargig.com/
http://www.auraplug.com/