[sticheno]

Couple hours short of 24, this has stopped over 400 in their tracks. Couldn't be more pleased! Here's a minor modification I recommend that helps the daily ritual of approving users and involves a minor edit to the user.php file. This is for those requiring the user to validate their email and then the admin manually approving:

We're running this on 4.1.0 PL2: line 1754 in user.php (may vary slightly in different versions), replace their mailto link and the following line that tells the IP (never figured out why we'd want to mail someone from the final approval process) and their not very useful IP check and instead point those to Google so you can see where those email addresses appear, and the IP to a decent WhoIs lookup. Most of my spam registrations come from Phillipines, Vietnam, Malaysia, India and my site is topical for something not practice there so this makes it super easy.

$cell[] = "<a href=\"http://www.google.com/search?q=$user[email]\">$user[email]</a>";
$cell[] = "<a href=\"http://whois.domaintools.com/$user[ipaddress]\">$user[ipaddress]</a>";

Of course every time you upgrade this will get wiped, but it's an easy change that really adds some value. YMMV. I'm shutting up now, happy.