Before you post anything here, please take a minute to see if your request or suggestions hasn't allready been posted here. Duplicates make forums like these that much harder to browse through.
Thanks in advance!
Since a lot of people are unable to use the Search function efficiently, here's a list of commonly requested plugins.
Deluxe Godmode - Allows for admins and users to toggle godmode
Custom Chat Colors - Allows for chat colors and tags on names based on admin flags (Source 2009 only)
Simple Chat Colors (Redux) - Allows for chat colors and tags on names based on admin flags (less options than Custom Chat Colors, but supports any game)