TheMadScientist - 1:36 pm on Feb 21, 2011 (gmt 0)
SIMPLE challenge/response: Easier than dreaded CAPTCHA, ask "what is three plus five?" and set your script to accept EITHER a case-insensitive eight or 8. Change it as often as you need. I've only had to do this in CMS's that won't allow me to filter input.
Yep, use something similar myself and what incrediBILL says is very true, but I don't always hide the whole form. (See Below)
Once they do that, they only need to find the form action.