I guess would be cool to draw some mhash/s chart somewhere in the main window (additional tab maybe), to monitor performance and stuff like pool uptime. I haven't seen this in any miner I used.
Actually, afterburner's gpu temperature monitor works fine, but it would be more cool like this

Also I suggest to change textboxes type such way, so after clicking in there I don't need to erase all the words like "Device name" or "Pool's name" or whatever. The text remains there, but after clicking on textbox it disappears allowing me to write something. Just a minor thing though.