Greg at Workalicious is looking for a wall mounted desk and has found a few, including this sixty buck IKEA number. They can be useful if you don't need a lot of space, and this one even has a key and enough room to store your laptop in it.
They are quite common in the hospital and industrial sector; this stainless steel unit folds down to 22" wide by 15" deep, and folds up to only 1-3/8" deep, so unless you have a Macbook Air you are out of luck for storing your laptop in it. From Lab Gear Direct
We have previously shown this contractor version, that you simply hang on four nails and take home with you every night, from Cool Tools
Greg also points out the Anthro eNook that has been around the back of computer magazines for years, but now comes in 36" wide models as well as the 28". It has excellent cable management and accessories, but looks a little commercial and is expensive at over a thousand bucks.
Lots of people make simple, basic units like this oak box that shows a computer being stored but has no wire management or accessory storage. From InstaOffice for $150
There is a very simple, elegant design by a Canadian architect that I cannot find anywhere. If anyone knows of it, please tell us in comments.