Real time search.
You guys have the Regular Expression evaluator but Sublime just does this right in the editor. You pick search, you have regular expressions on, it starts highlighting the matches. It makes a lot of sense. No Need for 2 UIs. If you want to try on some sample data just make a new file. Otherwise, it's far more common that I want to search for something in the current document using an regular expression.
I know you guys have incremental search but that takes you to the first match as you type. It doesn't show all the matches visible on the screen in the current document.