iLuv's Portfolio Stand for Kindle Fire is a nice, trim case that fits snugly and turns into a stand by unhitching the Fire from the bottom of the case. It's a design we've seen before with the iPad and works better than you'd think.
Drawbacks: this one isn't made of leather (it is very good faux leather, however) and it's fairly expensive at $49.99, though it can be had online for less than $40.
iLuv makes several accessories for the Fire, including a screen cover and other cases, but the Portfolio Stand gets the highlight image and the stamp of approval. We just wish it cost a bit less.