Yeah. A steam client would be nice. I don't use it all too often honestly, but it can always come in handy, and the more apps available, the better.

A protocol for conversations would be nice, but a full fledged client would be good as well.

Have you considered e-mailing Valve? From my (limited) experience they seem to be cool guys, and would most likely have no problems and might even help with some of the work.