"Nofollow" by default

Hi,

Is there a way to make all the links with "rel: nofollow" tag by default? It will be very useful for all the blogs out there...
I have found a mod, but it is giving the option for the nofollow... but I don't want to give the user the choice to make it nofollow or not! Here's the mod I have found: http://eugens-web.com/home/fckeditor_nofollow_mod

Is there a way to make this option a default when posting a link? Thanks