I prefer not to take my hands away from the keyboard if possible, since reaching for the mouse breaks my flow. For years I've used the Windows key or Win-R to start an app, open a file or run a command, but that has a few issues. It isn't very fast, it isn't customisable and it doesn't have good auto-complete.
QBar addresses these problems. It is very fast, it appears the instant you hit the mapped key. You can easily map any string to any command. And it auto-completes.
Since developing QBar I use it every day and don't know how I managed without it. I consider it one of my most useful tools. I hope you find it useful as well.
If you find QBar useful I'd love to hear from you. Or if you find bugs or would like to request a feature please let me know.