Deluge
One of the things I like in uTorrent which I'd love to see implemented in Deluge (my new favorite BT client, BTW), is the option of displaying upload/download speeds in the window's title. This allows me to monitor the speeds with the window minimized, since the title appears also as the minimized window's title.
Another option would be to alter the system tray icon to represent the speeds at which the bits are moving. Same as the battery monitor or WICD show dynamic information via the system tray. It's a waste of screen real-estate to have a static icon.
I'm sure many users would appreciate it.
-Ethan