I'd like to have more of a spacial sense of code. If only to help organize things. I work with huge fonts when coding (so I can lean back, instead of in), but in exchange I give up a lot of surrounding context. A sidebar like that would make organization a little easier. Not sure how it'd compare to a quick-jump list though.

Taking c++ as an example: It would be nice if when my cursor is in function Foo::bar() it highlights all functions in Foo which depend on variables modified by bar() and highlight all functions which modify variable bar() relies upon. Pretty trivial to do, but might be useful.