Signature Links for members 100 posts+

Do you know how to do this? Enabling links in signatures or just enabling signature only from an altering power or a post count, so i could decrease spam on my forum, so many idiots who post just to get the link in their signature and get some visits..


:D

I'll use signature links as an example of how this can be done.

Edit the permissions for registered users to not allow links in signatures.

Set up an additional usergroup that is allowed links in signatures.

Set up a promotion that will qualify registered members to become a member of the additional usergroup. This can be done on post count, reputation....