[RussEfarmer]

Chat logger would be REAL handy for stuff like this.. I wonder how hard it would be to smack one of those on there..

On a slightly related note, hatschat stores chat logs up to a point in a file called "savedchat.txt" located at GarrysMod\garrysmod\data\hatschat\. It has all of the color coding stuff in plain text, so it's pretty hard to read, but it IS saved if you ever have the need to access it.

Server side or client?

Client, that file is what keeps the text you see when you scroll up in the chat window (for hatschat)