Easy BotStopper as a highly effective phpBB modification which stops spam bots from registering on your forum. This MOD will stop bots from entering a website upon registration. Bots fail to see the input box for websites has been removed, and continue with the registration, which later fails.
Humans are completely unaffected by this, and registration will continue as it normally does.
This MOD was ranked in the #10 downloads at phpBB.com for several months in early 2007, and still rates very highly among users for its simplicity and effectiveness.
There has been an addon made to Easy BotStopper, by user "barky" at phpBB.com. To view it, go to http://www.cmxmods.net/v2/mods/easy_botstopper/addon.html
Download Easy BotStopper from the phpBB.com MOD Database