When users register, I would like to ask users a questions and get the feedback they return before I accept them into the forum. The problem is I have a lot of people who want to only hack the site to advertise drugs or what ever lately. My biggest worry is thinning out those jerks.
Hi and welcome to the nuthouse! ;)
Have a look on the mod site and do a search for "Spam".
There's quite a selection to choose from, there.
http://custom.simplemachines.org/mods