2 things.

1000 post limit or so for colors.
and
Give moderators a color banning ability.

Oh, and one more thing.  No Yellow or White!

The problem is that it woN,t stop the 1000+ post users from abusing colors, though. But yeah, personally IRC colors are useless for chat, IMHO. I don't mind Spybot having them, as it makes the new posts stand out and helps making the chat readable, but I think that's enough. If the entire chat starts having multicolor lines it's gonna get hectic to read, not to mention certain IRC users got a different background color and will not be able to read half of the text.

#omnimaga has no zero-tolerance policy towards colors, but if they are abused it is considered spam, anyway.

The only practical purpose I can think of for colors would be for a mod to send a message, but other than that, I can't think of any.  I think it would be best to keep the colors disabled.

I'd use them after using /me and messing up part of the message, to make the correction in the appropriate color.

If you leave them in a browser extension, then new people wouldn't know how to use it(We would hide Jim's code). Then when they ask for it, and we think they'll not abuse it, we could pm them the code to put in their bookmarks bar.

Well, with the browser extension, you could easily put an help page somewhere in a menu.