Admins! Don't give this forum up please!
(And spare poor Xiagan the work)Talked with Xiagan yesterday on IRC about the spams, and here is an SMF addon that may help (not older then 2 weeks, and installing it on my test forum was a breeze):
http://custom.simplemachines.org/mods/index.php?mod=2932Fairly new way to make a captcha, but if it works.. and it does

I have set up a
test forum that is already using appropriate captcha images

PM'd Xiagan some more details, and now i hope he can get that addon in, or poke Derek to do something.
Btw, there is SMF 1.1.13 out with some bug fixes, but nothing major that spambots could exploit from what i have seen.
I estimate the majority of the spambots that register here try to improve their google ranks by providing links to websites they want to promote. We can be lucky only a small fraction of these bots actually starts posting, as them collectively waking up would be a disaster. There are bots that registered months ago and still check the forum, although they have not posted a single thing.
Do you guys think its possible to clean the user database from most of these bots automatically? Most of the names are made following a simple pattern, that is
[a-zA-z]+[0-9]+[a-zA-Z]*, and many provide the same link twice in their signature... helps identifying them automatically.
Lastly, if that helps anyone i set up a little trap for those nasty email harvesters
here, in case some are here. Hopefully these stupid bots pick up the URL and spread it, as it is also in my sig.
(Someone has to do something, right?)Oh, and this:
http://en.spambot.pl/ <-- i lold. Shame on them.
EDIT:
From their site:
Protection against the program
The protection of one’s own websites against the program is included. You simply need to upload to your website server a file entitled ‘spambot.txt’ with the content ‘spambot.pl’. If the program tries to spam this page, it will be announced that spamming can’t be done because there is the file ‘spambot.txt’ on the server. Before spamming, the program always checks if there is such a file on the server.
Worth a try imho

EDIT2 (half a day layer):
Geez, more spam posts... If you let me, i'd help deleting stupid bots and cleaning up the forum

EDIT3: Another mod that looks promising, just updated today, now works with SMF 1.1.x:
http://custom.simplemachines.org/mods/index.php?mod=2502EDIT4: The images i used for notCaptcha can be found
here