I (as a user) would very much love to have a plugin that would work like the 'go to file' feature in Textmate. When you execute the keybind, it opens a popup window with a search box and a list of all the files in your project. If you start typing it does a fuzzy search for the filename and it always selects the top option. If you press enter it opens that file or use the arrow keys to navigate the search results. This allows for _very_ quick jumping between files in the project wether they are already open or not, and it's a real time saver.
Example (taken from the internet): http://i.imgur.com/zdPjv.png