We've shortened the initial list of categories that new users see. We took a look at which were the most frequently used categories and removed those that were seldom used. This makes the initial list easier to browse and select from while also raising the visibility of our "Add a category" option:
Note: if you don't see a category in your drop down, simply click on the Settings menu and choose Categories to view the whole list. Click the checkboxes next to the categories you'd like to see on your list and you're all set.