> the flatulent gem provides brain dead simple ascii art captcha for  
> ruby.

Hmm, maybe I'm missing the point, but aren't these really easy for bots to
decode?

Looking at the examples at http://drawohara.tumblr.com/post/4791838
I see that random ASCII characters have been dropped around. But these can
be removed trivially, e.g.

   gsub!(/[^\/|\\_()\n]/,' ')

Only minimal damage has been done to the original characters, which are now
easy to pattern-match. It therefore seems that the randomly-strewn
characters have the effect of making it more difficult for visually-impaired
users to access the site, but cause very little impedement to bots :-(

Now, if this ASCII art were turned into a PNG I guess that would make it a
bit harder - although not much, since it's pretty trivial to OCR a clean
grid of ASCII characters back to ASCII, albeit more computationally
expensive.

Perhaps this captcha will be useful if very few sites use it, so the
spammers don't bother writing a decoder. But in that case you don't want it
used by "the masses" :-)

Regards,

Brian.