ForumName2 by default adds peoples' guild notes next to their names in chat messages (including system messages). It also has support for custom notes. Access the custom note configuration through the interface options menu, /forumname, or /fn.
Based on the mod ForumName by Omni of <The Basin> on Tichondrius, updated and modified with his permission.
Added check for GetGuildRosterInfo return value to ensure a valid character name
Fixed a bug where names didn't work with class colors enabled