Yes.

Does one exist currently? No.

Would it make sense to write one right now? Only if you did it on the PTR since the combat log system is entirely revamped and anything you do on live will need rewritten for 2.4.

Is anyone likely to write it? No. However I believe with the new system mods like Mik's Scrolling Battle Text and other SCT type mods will be easily hacked to suit your needs.