It's built-in! Right-click the search box and "Add as search engine". Then pick a keyword like... github. Then you can put in the omnibar:
github samirahmed
I use this, however unfortunately under Chrome, it does not provide all the same functionality as using the command bar directly.
For example, type 'github my notifications' in Omnibox.
It takes one to the advanced search page, instead of the notifications page.
I wonder why it's different, doesn't it go to the same URL?
It's not quite the command bar, but GitHub's search box uses OpenSearch and Chrome picks it up. You should be able to type `github.com`, hit tab, and then search GitHub.
> it would be incredible if the command bar could be integrated into my chrome omnibar...
That's pretty unlikely, though Firefox probably provides deep-enough hooks to do so.
Alfred can do that if you're on a Mac.
http://alfredapp.com/
How?
My fingers tremble at the thought of mixing this with Firefox's completion and the Pentadactyl command line.
that way i could naturally use the power of the commandbar in my browser without having to go to github first