Question Register Plugin
This hack adds a question to registration process that the user must answer before proceeding. You must have the AccountManagerPlugin installed to use the plugin.
The objective of the plugin is to exclude standard robots from registering.
If you have any issues, create a new ticket.
Download the zipped source from here.
Install this plugin
If needed, edit your conf/trac.ini file and enable the plugin:
[components] questionregister.* = enabled
This plugin was developed for Estobuntu, a remix of Ubuntu for Estonia.
It is loosely based on the work of RecaptchaRegisterPlugin, so it's GPL licensed as well.