Since the HD goes with me everywhere, I needed a case, and I found a really inexpensive one on Amazon. The Poetic Slimline Portfolio case adds very little bulk to the HD, but it protects it from bumping around in a backpack while still giving access to all ports and buttons. (The picture is a live link to the case on Amazon.)
It even offers a magnetic sleep/wake function. I actually hadn’t realized the HD had sleep/wake until I saw the feature in the description of the case.
The magnets hold the case closed, and I’ve not yet had it pop open when I didn’t want it to.
The roll up stand function is only OK. It works, but it’s not as stable as I’d like, especially in the most upright pose. The case I have for my Nexus 7 is a much better stand, but it’s also bulkier. I do like that the Poetic case folds back completely, so I can lay it on a table and “write” on it comfortably.
It comes in a variety of colors, although the black is the least expensive, and is the one I purchased. If you’re not in a hurry, you might want to watch the pricing. It’s currently $12.95, but when I bought it a few weeks ago, it was $9.95.
If you’re looking for basic functionality and don’t need something fancy, it’s an excellent choice.