http://forum.us.runesofmagic.com/ - official US forums, more info, almost no GM involvement
https://forum.runesofmagic.com/forumdisplay.php?f=41&langid=2 - Official EU forums, less info, more GM involvement
http://www.theromwiki.com/index.php/Main_Page - The Curse RoM wiki
http://runesofmagic.wikidot.com/ - 90% quest info/walkthroughs, have to use search function to find anything
http://www.zam.com/wiki/Runes_of_Magic - mostly quest info, stops at about Aotulia Volcano, often lacks walkthrough info
http://rom.curse.com/downloads/rom-addons/default.aspx - Curse.com AddOns
http://romdata.getbuffed.com/ - RoM database site, not updated (3.0.3), sometimes invaluable comments
http://www.runesdatabase.com/ - another RoM database site, updated (3.0.5), no comments
http://dawn-treaders.info/sw/#tabs-2 - Siege War database site