THIS ADDON IS FROM chicogrande (jluzier@gmail.com)!
I have only done the changes to make it compatible with Patch 2.4
The outdated version can found here:
http://www.wowinterface.com/downloads/info4720-TitanPanelGuild.html

Titan Panel [Guild]: A simple guild list for the Titan Panel AddOn.

Requires: Titan Panel
Can be found at:
http://wow.curse.com/downloads/wow-addons/details/titan-panel.aspx
or:
http://code.google.com/p/titanpanel/

- Lists online guild members in a tooltip
- Menu shows names of online members, with click to /whisper functionality.
- Menu has options to /guild chat and /officer (/o) chat
- Menu has option to toggle Show offline members, which changes this setting in your Social frame, Guild tab
- Advanced menus to /w, /invite, /friend or /who guild members
- Shows default messages if the player is not a member of a guild
- Updates the guild listing every 5 minutes to accomodate the GuildRoster() delay and lag. The update only takes place if the player is 'idle' and not accessing conflicting UI frames or Titan elements
- Tooltip and right-click menu content is sortable using the Sort menu option, works like the guild frame
- Filters available for seeing only those guild members within your level range, your zone, or to look for members of a specific class
- Colors rank names (Advanced) or player names (Simple) based on rank index
- To save space, player can turn off menu options

Usage:
- In the right-click menu, click on a guild member name to send them a whisper
- Enable 'Show Advanced Menus' to create submenus for each online guild member based on rank
- Left-click on button to toggle the Friends Frame > Guild Tab
- When you have all settings configured to your liking, use 'Hide Options' to maximize your menu space.