Standing workspaces

Why sit when you can stand?
(Ergonomically speaking.)

Or better yet, alternate between the two on a regular basis!
(every half hour or hour)

DIY simple standing desk
(it's not freestanding, it sits on your desk.)

Notes from the comments:
+It's important to have good cushioning for your feet, be it a carpet or good shoes.
+You might hurt your back by having to bend down on a regular basis to write things on your desk.