I've seen two or three in my time on Facepunch.
Problem is, every one of them broke chat text hooks used by another chat monitoring (ULX "!<command>" stuff for example)
And, they're all probably broken now due to age.
It _
might_ be possible to not break chat text hooks, but, would be darn difficult.
See iChat -
http://www.facepunch.com/showthread.php?t=658987Can't find any other. User "Conna" made GME, but it's even older and I can't find it any more.