For every interested person that signs up for our site, I get a dozen or more junk registrations. You know the type. The meds, the enhancements, the playmates, the software (fully functioning, of course), xyzzy, all so unimaginative. Such a time burner. I'd rather be writing stories (or at least critiquing them) than wading through the week's spam registrations.
One solution would have been to simplify the new member registration form. Currently, I ask for a bio and home base from prospective members to get a bit of a feel for who is applying and whether they are truly interested in our group, or simply trying to crash my registration system. While this information helps us to know our fellow members, it is just the kind of things that robot spammers like to find: blank spaces in which to post junk. Ditch the excess information, and spambots are less interested in playing in our sandbox. Gawd, I hate having to second guess every kiddie out there.
Always looking for a better solution, I learned about Mollum. Mollum is a service that watches what gets entered into an online form and looks at the text to determine whether it was entered by a human or a bot. If it can't decide, it throws a captcha as a final bot trap. This does mean that text you enter into forms is going to a third party service for evaluation, so if that bothers you, don't post (chat room and some other pages are excepted). This is new (to me), so if you have feelings about whether the service is a problem, please let me know. For more information about Mollum, check out: http://mollom.com