Hiya Falko and Tim Howabout using the same Captcha functions that you use when creating content or adding a comment to a howto for the forum here? I just noticed there's been quite a bit of spam focussing here. sjau
I'am not sure if the spam is submittetd by scripts bots or "human bots"... There is a captcha when you register a user in the forum and unregistered users are not able to post.
There are plenty of methods to circumvent captchas. In the okopipi blog there were a few ways on how to do it and I just think the one of the drupal is a lot harder to crack then the one of vB... Another possible thing as captcha would be like a question: What is the capital of India... or how many states does the US have or the Marseilleise is the national hymn of what country or or or....
Add-On: This guy here has decoded a lot of captched - e.g. vBulletin - but not yet Drupal http://sam.zoy.org/pwntcha/