Narro
Description
Narro is a web application that allows any number of people to translate at the same time. One ore more coordinators can be nominated to supervise the process.
Narro can be accessed here.
How it works
In Narro, a text can have several translation suggestions. A regular user that has registered can add suggestions and vote other suggestions. However, for those suggestions to be used there has to be someone with validation rights. In order to get validation rights, please send your request on the dev-l10n mailing list specifying your Narro username and language.
If you're the only one who translates, you can validate automatically your suggestions when you're adding them, so don't worry about wasting time.
Narro pulls nightly updates from mozilla's versioning system, so your only job is to translate.
You do have to export your translation and commit it to the versioning system yourself once it's finished, that being a Mozilla requirement right now. Don't be afraid to ask for assistance on the dev-l10n mailing list for this.
After you export your translation, you'll also get a language pack ready to be installed and tested.