gnu-social/plugins/Autocomplete

Autocomplete allows users to autocomplete screen names in @ replies and
! group references.

When an "@" or "!" is typed into the notice text area, an autocomplete box
is displayed populated with the user's friends' screen names or group
memberships.

Completion suggestions can be selected via the mouse or arrow keys, and the
suggestion can be inserted either by clicking or hitting tab. Hitting enter
will also select the suggestion, but will submit your message too!

Installation
============
Add "addPlugin('Autocomplete');" to the bottom of your config.php
That's it!