There's loads of things to stop spamming floating around... Seems using a combination of methods would work well. Ie. using cookies, banned log file, add confirm etc....
Glenn
Links 2 Mods Site:
http://cgi-resource.co.uk/pages/links2mods.shtml
Glenn
Links 2 Mods Site:
http://cgi-resource.co.uk/pages/links2mods.shtml