What do I need for a rabbit cage, and how big should it be?

The rabbit should be able to spin around and stand up, things like that. It's definitely very important that they have an area outside the cage where they can roam. A big exercise pen or a rabbit-proof room that they can roam around in is perfect. Make it as big as it can be, as long as it's rabbit-proofed, so no cords and no carpeting. Carpets can be a little tricky for some of them.