The Standing Desk:
I moved into a new apartment in August and found myself without a desk for the first time, so I decided to build one out of IKEA parts.  I felt very lazy and too comfortable sitting, and the time spent at the computer was probably negatively effecting my health.  Here is how I built my standing desk. 
Unfortunately, this desk is at a fixed height; it is difficult to make minor adjustments.  Adjustments in ~1 or 2 inch increments are possible by changing the thickness of the table, the height of the CAPITA legs, or adding dividers between the legs and the EXPEDIT bookshelves.  Standing on a mat may also make work more comfortable.
List of Parts and provided height:
2x 
EXPEDIT 2x2 Shelves 
(36")1x 
VIKA AMON Table 
(1 3/8")1x 
CAPITA Legs (set of 4) 
(8")Additional Parts:
1x 
CAPITA Legs (set of 4) 
(8")2x 
EKBY HEMNES Shelves 
(desk extension)The desk totals to 43 3/8", but probably sits a little shorter as it digs into the carpet.  This isn't the cheapest way of creating a standing desk (my friend just places a chair on a table), but it comes with a bunch of shelves, and feels like a full table, which works great for me.
I've been using it for over a month now, and really enjoying it.  My only complaint is that it gets tiring after 5 or so hours.  I'm going to have to find a stool soon! >.<