The $40 Standup Desk
An inexpensive standing desk is nice, but I don't think I would be any happier standing continuously than sitting continuously.  Unfortunately, rapidly adjustable sit/stand desks are insanely expensive.I think this person has found a heck of an in-between position.  It's not $40, but it's a heck of a lot cheaper than a geekdesk.
http://blog.melchua.com/2011/07/09/fitting-yourself-a-sit-to...