Open user registration
From Achievo/ATK Wiki
There isn't any "official" atk best practices for allowing users to self register to a web site. A few attempts have been made though.
jgarifuna's work
Probably the first one to seriously attempt this (or at least share code).
MySHI
An open-source project that shamelessly copied and butchered jgarifuna's work but added support for the atk language files, themes, and config settings. There are also numerous tweaks for the MySHI application. Also started pavying the way for a custom security manager which will be necessary for some future updates. Also handles email confirmation differently than password creation.
Note that if you download the site it's original configuration is setup for a single user setup so you'll have to tweak things to see the user stuff. steps are on the wiki
If you do give feed back there is already a list of todo's on the tracker. under the security group. MySHI security tracker