I've made a few adjustments over the last couple of days to improve the usability of the website.
The navigation at the top of every page within a project now is completely revamped to provide horizontal and vertical navigation.
An example of an item page, with links to adjacent items in the same folder and links to go back to the folder or project.
An example of a multi-part item page, with links to the previous and next parts and links to go back to the list of parts, folder, or project.
Next, progress bars now show two things. Dark blue still shows the amount complete. Medium blue shows the amount pending. This will help provide a better sense of accomplishment and enable you to see true progress even when your suggested translations have not yet been approved by other users.
Finally, each user profile page now shows statistics. You can see how much you have done by clicking "Your Profile" in the top navigation bar.