Free VSTs

http://www.tweakbench.com/

This site has filters, delays, synths, many others. very useful, A+

http://www.ismusic.ne.jp/slim_slow_slider/vst/index.html

Japanese site, but some useful plugins here too.

http://www.digitalfishphones.com/main.php?item=2&subItem=1

some nice free effects, and good production hints and tips !

http://www.kjaerhusaudio.com/classic-series.php

First class plugins unbelievably free !