As I mentioned in another post, the inputPanel introduced in the latest beta is a wonderful feature that allows you to evaluate expressions without having to close the command prompt window every time.
Unfortunately it has one downside compared to a full interactive shell: no history. In ghci (the interactive shell for haskell), if I make a typo or want to change something, I can just press the up arrow and make any necessary changes. Unfortunately that doesn't work for the Sublime inputPanel, which means you have to do a lot of retyping.
So my request would be to add a history to the inputPanel that you can browse through with the up and down arrows, just like the way the command prompt works. It would store every command entered in it since Sublime was started, or, if that takes too much memory, just the last 20 or so items.
In my mind this would make an excellent feature even better, since you can then forgo command prompt windows entirely.