QUOTE(geoffmerritt @ Jul 14 2009, 11:42 PM)

If you don't want urls sent in your form, this code will check the string for 'http', which are in all spam emails and if detected will stop the script.
Unfortunately this produces huge numbers of false positives, since lots of genuine emails also include URLs.
FWIW, I'm using PHPBBS for a forum, and almost immediately (despite the CAPTCHA thing) I got a regular trickle of spam signups. This stopped completely when I added a "Pass question"
viz: "Does Imaginatorium Shop sell: (SELECT) Watches Puzzles"?
"Watches" is the default, and the wrong answer; no signup script so far has bothered to try to work round it.