In reply to Jens Nilsson (@_jensnilsson).

I tried that one out before building Quick Navigation Interface, but I didn't really like how it was built. It uses an AJAX call to search for content, so it takes a second to get your results, while QNI caches an index locally, so you get them immediately. That does have the benefit of being able to search large amounts of content, though; QNI limits its index to 500 posts, to avoid performance issues. (That can be configured, though, if users want to trade a little bit of performance for a larger index.)

Dashy and WP Hotkeys also offer some similar functionality.