The mess of cables on and under my computer desk was out of control. I couldn't vacuum under the desk, I'd get my feet tangled in them, I couldn't unplug anything without yanking something else out and it just looked messy. The list goes on and on.
To create a solution to the problem that can be had with little or no money and little expertise, while utilizing stuff around the house. Nothing elegant, just simple and utilitarian.
First, a bit of background on the desk. I like mine simple and clean. My computer desk consists of an old cubicle slab on adjustable legs. The legs are adjustable from Rockler and are $39.99 for the set of four, the slab I got from my employer for free, its very sturdy and heavy. That's it. Slab on legs.
Drill bits (sized for your fasteners)
Bolt cutter (or hacksaw if you need to shorten the length of the shelf)
Length of Closet Maid or similar wire shelving (I used a 3'-0" section)
Closet Maid or similar plastic end caps
(2) steel angles (2 per 3'-0" of shelving, I'd recommend one additional angle for every 1'-0" or so of shelving)
Wood screws (lengths based on your desk thickness)
Zip ties in assorted lengths (I used the permanent ones, you can use the reusable ones too)
Gardner Bender or similar cable management clips (I used the Gardner Bender SnapSHOT MultiCable Staple)
All your spaghetti of wires under the desk
All of the above materials can be found at your local big box home improvement store. I got lucky and had all of this stuff lying around the basement, so this only cost me some sweat and elbow grease.
Be sure to check out the pictures at the end of this instructable, they show important details.