Nokia has released three Angry Birds themed hard covers for the Nokia Lumia 710. They fit around the back of the phone, over the battery cover, providing additional protection and an eye-catching design. In protection terms these half-cover cases offer a decent alternative to the silicon style case, but not the same level of security as a full case.
The other way to change the look of your 710 is to change the battery cover itself. In some markets the Nokia 710 ships with an additional battery cover in the box, but if not, as shown below, you can now buy any of the standard covers (Fuchsia, White, Yellow, Blue, and Black) from Amazon, with pricing starting at £10.