I'm a nomad programmer, a bedouin, and often find myself working at cafes. At the end of a particularly cafe-heavy week I found myself with an awful tension headache due the miserable ergonomics of sitting down and staring at a laptop. At home I can use my standing desk, but I'm yet to find a cafe where I can stand and code.
Here's what I did about it:

Super-simple design: two triangles (with feet at the bottom) connected by a piece of wood. I notched the connections but it worked fine without them. The white stuff is some foam I had around.

And here it is out in the wild:

I plan on this version being a prototype, and am hoping the folks at the local hackerspace can help me with a metal or plastic version. However, this first draft already works and is shitty enough to inspire you to make your own, better one. Hack on!
c2