I am suggesting this because of one thing. People who sign their posts with their names is *bleep*ing annoying me. So when someone goes like:

hi i r new here welcum me thx bai

thx,

n00b

you could filter out the thx, n00b part. This is good because it saves database space, and also a bit (but not much) of bandwidth. Especially useful for larger forums.

(I suppose it could also be useful for larger phrases which commonly get people banned, such as "Click here to join my forum" or "Go to this site to see some *edited so I don't get banned* TODAY!!!" or something (sorry for the examples but they are rather common).

Hmm, regexp-style word filters would be nice :)