Now that Rift supports addons I'll be playing with the API over the next few days and getting a few small addons complete. My current task list is:

 * TableInfo - inspect LUA tables

 * LibNotify - Growl like notifications system

 * ChatAlert - notifications on incoming chat messages (supports filtering)

 * CombatAlert - notifications on combat events

 * LUAPad - In-game LUA editor

 

Should be fun :)