"[Trade channel] - Légolàss: LOOKIGN FOR A GRP!!!!!!!!!!!!!!!!!!!111" -> Thanks for the hint.
This is a really really small and simple addon which adds a "ThanksForTheHint" to the right click menue of a player (and their names in the chat). After clicking it, the name of the player will be colored red from now on in the chat window.
I've wrote it because I'm doing a lot of random group instances and I like choosing them by reading their LFG-messages in the LFG channel. I used this addon to mark people whose LFG-messages I whould think twice about before deciding to replying to them ("Légolàss" whouldn't needed to be marked, he already marked himself :-).
There are a lots of other addons which can do that (and much more), but I just wanted this small feature.
It doesn't has anything to configure, you can't choose colors and you can't delete people once marked, it only does this small marking thing.
Maybe some other people can use it too.
Note: This addon probably doesn't work well together with any other chat frame addon.