The two main things I'd like improved in the Gonvert UI:

• Be able to select "from" and "to" units, and then enter new values for conversion without having to go hunt for them again. Right now, for example, if I want to convert length/width/depth measurements from imperial to metric, I need to scroll to the "from" unit, enter the number, scroll to the "to" unit to see the result, scroll back to the "from" unit to enter the next number, etc.
• Be able to mark certain units as "favorites", and then have a "favorites-only" view mode. The very comprehensive list of units is a nice feature of Gonvert, but most of the time they just get in the way; it would be nice to have the option of seeing all the obscure units only when actively looking for them.

NIT Units Converter for Diablo actually looks a bit closer to what I want, but it hasn't been released for Fremantle yet and is still missing some important units (like the entire "temperature" category). I'm hoping that one of these two apps can implement the features I want from the other one sometime soon.