This is a hacked-up version of "Talk To the Hand" which allows you to hide posts from specific users. It only puts the (x) on posts in communities, since avoiding their other posts is easy. (defriend them!)
This edition was originally developed for the Expressive layout; user eman reports that it also works with Mix-it. You need to modify the @include field above, replacing 'YOUR NAME HERE' with your username.

Updated 10/8/07 -- Should now work with newer GM/JS/Firefox -- not sure which one's upgrade broke it, but one of the variable names in use is now reserved, and was breaking.