Now these plugs are not free, but only cost around $39 each, and they are free to evaluate (and there is no limit on the eval period).  My favorites are 1973, Vibe EQ, Event Horizon, and the very cool Bad Buss Mojo.  Give these a try, as they are very easy to use, warm, and free to try.  Oh, two other things, they are 64 bit precision within (NICE) and there are x64 versions available for those who have made that computer/OS jump to 64 bit.

Stillwell's site