Amnuts is a talker base code, created by Andrew Collington. It's been around for a few years now, and has gained in popularity. It's free for anyone to download and start up their own talker/chat room, and the website is setup to help you out with any problems to do with the code.
It's a little different from the ewtoo and pgplus talker codes, in that it's originally based on the NUTS code, by Neil Robertson.
Pretty easy to pick up and get going, the code is located at http://amnuts.talker.com/.