Are Sigs Still a Viable Source of Advertising?

***I posted this on another forum, but haven't gotten any replies. Hope posting this here will get at least a few.***

Have any of you found, since all the sig selling/whoring, that the number of clicks through your sig have diminished?

Have the number of signups you get decreased?

What about the quality of the sign up? Have they been more/less active or stayed about the same?