Firefox extension which stores URL shortcuts?

I’m looking for an addon (I don’t know what keywords to use in the extension directory) which will, ostensibly, shorten a URL, but locally (i.e. not just some bit.ly or other kind of url shortening service.

As an example, I type simply ‘b’ and hit enter, and it loads reallysuperlongandcomplicatedurlthatihavetoopenamilliontimesaday.com.

Opendns.com has a dns hack that lets you do this, but only if you proxy all of your requests through their servers, which I don’t want, I’m just looking for a way to do it locally.

I know the super-complicated way of doing it would be to utilize my own local dns server, but I don’t want to go through that hassle, there has to be some sort of browser extension! :P