When I bought my pocket PC a few years ago I bought a rhinoskin aluminum case for it. I was always impressed how well it protected my pocket PC.
I didn't know there was a Gameboy Advance SP version of the rhinoskin until I was at Toys R Us yesterday and there it was. Only 5 bucks. I immediately bought it - it was a no brainer.
So I've got my GBA SP installed in it and I'm VERY impressed. The case itself is made of aircraft aluminum (at least the pocket PC ones are, I assume this one is too) and has a foam-like covering inside to absorb shocks and avoid scratches. It looks and feels fantastic, and it seems just as sturdy as my pocket PC one. I'd recommend anyone that doesn't have one of these to pick one up, it's great. I'd give it a 9/10 - the only thing I don't 100% love is the weird folding mechanism near the GBA screen hinge, but I figure it's probably the only way you could set it up. It's a little weird, but necessary, and well implemented.
Here is a review at the Gadgeteer with more pictures (I took the above pictures from this site): LINK
Anyone else have one of these?