Aww, yay indoor home You could add a box for her (or is it he, I can't remember your buns gender though I'm pretty sure she's a she ) to hide in. Just any cardboard box with a hole cut in the side works, she may even end up jumping on top of it! How tall is the cage? It almost looks tall enough that you could add another partial level if you wanted, though the perspective could be throwing my judgement off too.
Oh, I might also give her a litterbox too if you don't have one, it will help keep the rest of her cage clean and make your job of cleaning much easier too
How about wrapping the cage with an x-pen? That way she would have more room and you could have the space to provide a hidey spot (like a cardboard box), a litterbox, a bed area and some toys. Oh, and also some place for her hay (which I don't see anywhere in the photo) And she'd still have room to run around and binky.
With an exercise pen, it can be set up with the ends against a wall and the cage placed in that space. But you may want to set the cage on the floor (not in the stand) so that she can hop in and out of the cage more easily.
The photo below doesn't have the cage inside, but it shows how the x-pen can be configured to allow for more space. Just imagine your cage within that space (maybe under the window that's in the photo).
It'd be nice if you could add a litter box and put a big fleece on the rest of the bottom of the cage. Also, it is nice if you can put an xpen, to give lots more space for exercise and play.
Also, a tunnel might be nice if he had an xpen or something that provides more room- Ripley spends SO much time in his like this: http://www.newegg.com/Product/Produ...KP-_-pla-_-Small+Pets+-+Toys-_-9SIA00Y0915277