firefox url bar handler

I have an idea about a plugin to write for firefox, but have no idea where to start, so any comments would be welcome. I have a few sites that I need to query several times per day using a certain ID. I'd like to be able to type in the url bar some sort of identifier followed by dash followed by the id (e.g fid-123) I'm trying to query and make firefox do something in the background and fina开发者_JAVA技巧lly redirect me to the correct URL with the respective .

I've been toying around with greasemonkey but doesn't seem to fit the purpose. Has anyone done anything similar or knows how to go about doing something like this?

---

You can make a bookmark with %s in the querystring and fid as the keyword, then type fid 123 in the address bar.