As a member and operator of the #vampyreinn free-form roleplaying channel, first on DalNet and later on Sorcery.net, I programmed a custom bar-bot capable of interacting with patrons in-character and in natural language.
If you would like to use it in your own channel, you can download it and customize it to your heart's content so long as you have a Linux box to run it on (i.e. it's not a mIRC script or anything like that, but a separate IRC client program). There are intructions inside the archive.
Download vibot v0.5 (43K)
This program is released under the GNU General Public License.