On the web side of the Mozilla project, two more areas are in the process of being localized.
A small but very visible side are the snippets of text that show tips to users in the Firefox Start Page, these tips are being covered by this bug so if you can help on this, do not hesitate:
The second and much bigger localization work, is the translation of the soon to be released new Add-ons site (project Remora) that will be entirely multilingual. Mike posted a long and detailed post that explains how to help with this:
If you want to help for these projects, it is important to communicate about it within your local community so as to avoid duplicating work. To give you an idea of how much work it is, the AMO translation into French took me about 5 hours.