CodeGoo is already a Firefox add-on that makes it easier to work with your projects in Google Code.
Using CodeGoo you can track multiple projects, search the various Google Code tools (such as the issue tracker, SVN and wiki) and add new issues with a single click.
My addition to CodeGoo will now be to make it work with Sourceforge.net projects as well as Google code. I already have alot of this working and have dynamic menus depending on the projects website.
I also need to re-do the code for addng issues as this seems to have a bug and doesn't work with projects in Google code at present.
If I have enough time I would also like to enable the user to generate a DOAP file for a project. This can be scraped from the Google Code pages.