Through the years, I've listened to users clamoring to have avatars & sigs (and ranks and karma and blahblah) and wondered "Why? Why all that crap? It's visual clutter!"
Try to preserve the integrity of the searchindex table by giving 'em sigs as containers to put their silly stuff in... and they balk, and STILL clutter their posts with non-topical content.
Yeah, clearly, obviously, sigs are often intended as self-promotion... but their linkback/SEO/SEM importance had never occurred to me, until now!
So, kick me and tell me I must've been living under a rock or something. Ah, the 'angles'. Such ingenious little buggers we netizens are.
^--- C'mon admit it, that's the right thing to do.
Now that reminds me, back in the day...
To the great chagrin of the users, I customized our veebullshetin threaddisplay script so that a participant's sig was displayed only ONCE per thread (within their first post)... and noticed shortly thereafter that our ranking for targeted keywords in major the search engines (Excite, Google and Yahoo, at that time) really improved. I never put my finger on the reason (hey, my time was spread waaaaaay too thin)...
If you manage multiple sites & can play around with changes and make comparisons, I think there might be more (merit) to this than "the right thing to do".
Server specs (Server OS / Apache / MySQL / PHP / DragonflyCMS):
DragonflyCMS version 18.104.22.168
Joined: Jun 29, 2004
Yeah, page rank is a mighty river that gets siphoned off into tiny tributaries of sigs. I really like the automagic sig nofollow. (Until I noticed it while trying to get spiders to a new site, LOL. But like I said there are other ways.)