Thud and Blunder

Eldre'Thalas

IGuildTradeSkill v1.2.1. Shares guild tradeskill data to make it easy to coordinate crafting between members
Omen Threat meter. Shares threat data between members of a raid, to allow the members of the raid to gauge the maximum safe level of DPS and healing, and to allow the tank to identify party members likely to steal agro.
CharacterProfiler Collects data for upload to the guild's WoWRoster database (a "super-Armory"). Use UniUploader to upload your data file after exiting WoW. See the upload links above for what to configure in UniUploader.
Grid compact unit frames for monitoring healing and buffs
Big-Wigs light-weight and efficient boss mod
Talented talent management system, useful for when you respec often

Rare crafting on Eldre'Thalas WoWWiki page, add yourself!
warcraftlist like Craigslist, but for WoW
Blacksmithing guide in Blizzard crafting forums (includes skill-up guide and lots of useful info)
Enchanting skill up guide (to 300)
Engineering skill up guide (to 300)
El's Anglin' fishing information
WoW-Gem nice gem calculator for finding the right gem for your needs
(currently broken)

World of Roguecraft great lockpicking guide (this is from archive.org, as a gold seller grabbed the original domain)

MapWoW.com like Google Maps, for WoW. Shows herbs, ore, and treasure. Zoom and pan and highlight exactly what resource you want to farm. Extremely useful for farmers.
interactive map of Northrend
Gear Wishlist shows what gear upgrades are available for your character
chardev.org another gear upgrade calculator
WoW patches get the torrent at the end of the list for a given patch
uTorrent excellent BitTorrent client for downloading WoW patches