Timeline - Official history of Rubi-Ka.
Prophet without Honor - A book set in the universe of Anarchy Online.
Animated Series - A series of animated films set in the world of Rubi-Ka.
Socialfly on impersonating storyline characters - Ex-director of ARK events department's post about impersonating storyline characters.
Beginners Guide: Storyline and Events (by Lornavash)

News Magazine
Newland News - 'In character' news magazine reporting on role play and social events on the Rimor dimension.

Online Radio Stations
Gridstream Productions - Internet radio station providing great entertainment ingame. Tune in at their site, come to the party, meet the DJ ingame.

AO related pages
Auno - Great source of AO knowledge: item listings, nano listings for various professions, character info, etc.
Anarchy Archanum - Useful guides on quests, unique encounters, tradeskills, etc.
Anarchy Universe - A vast resource of AO knowledge. A lot of useful guides (the most up-to-date ones, I should add.) Forums.
Anarchy Online Vault - Guides on quests and tradeskills.
Shadowlands Library - Guides on garden key quests mostly. Some are a bit outdated.
AO Pocket - Symbiant listings. Very useful.
AO Tradeskills - Very good source of knowledge about tradeskilling, especially the alien tradeskills. Includes components' ql calculators.
AO Warcry 
Halorn - Good source of utilities like Clicksaver.
Wikipedia - AO wikipedia.
Wikia - Another AO wikipedia type site.
Helpbot store

Utilities
Clicksaver - Great utility. It finds a mission with a given item as a reward.
Atlas of Rubi-Ka - The most up to date version of AO map. It includes both Rubi-Ka and Shadowlands areas.
CSP Map - This map not only shows all the cities on Rubi-Ka with their names (unlike the original one) but also all the cities, tower sites, wompahs, grid points, shops, quest NPCs... too many things to list them all here.
Nano Nanny - A little program that helps you design implants.
Unity of the Rose Agg/def calculator
World Clock - Nice utility for figuring out the time zones: just choose the date and time in GMT/UTC and it will show you the date and time in your area.