I've noticed on my phpGedView website some attacks by spammers starting in December 2006. They are registering new accounts automatically like SUNTZU. Because of different names it is impossible to filter them in code (like SUNTZU patch does).
I created a little patch to login_register.php to use CAPTCHA (http://www.captcha.net/) in very simple way. As a matter of fact, it adds a question "2*2=" and user has to answer "4" :^)
This patch is for 3.3.8
I've patched also two files: lang.en.php and lang.pl.php - now they contains strings used by captcha patch.
In spite of its simplicity I hope it can be useful for somebody.