WowAce

Suppress chat messages when specified items are looted

Advanced Chat Filtering and Spam Blocking Addon

vChat

Small addon to copy chat lines.

Converts incoming ALL CAPS CHAT into lowercase text.

Make noise when the servr is going to restart

Provides bang-whispers for your professions.

Shows guild and system message of the day only if either one of them has changed since the last login.

Shows you a typing indicator when people are typing to you.

Enables cooldown notification between players and allows party members access to each-others spell books.

Send Mail to Groups

Allows raid leaders to view information on raid or guild member equipment information

Colors friends/bg score board/who list names by class color

Congratulate people when they ding

Automatically sends guild recruitment ads to the GuildRecruitment channel.

Bug fix for the Blizzard calendar -- prevents unexpected window closure while editing events

TalentWhisper

Alert your friends when you ding, get an achivement, or get phat lewts!

Shift-clicking on a user name in chat shows a tooltip with their whois information.

Locks the chat window tabs to prevent accidental undocking via mouse drag