Velcor straps, as used for RC planes & cable management are the way to go. They are awesome in so many ways. For instance, If you want to add a new cable, you can either velcro it to the existing strand for cabeling speed, or simply undo each strap, add the cable and re-close it which isn't much slower. Cabeling is SO easy now! Just don't use too many of them or you may find them obnoxious, I used about 1 strap every 2ft.
My gaming PC has 7.1 surround sound (an old logitech 5.1 plus a stereo kit for the sides...) so I have a 8 individual cables right there...Tons of cables, pluse USB gear (HDD docks, Cell and Mouse charger, etc..)
Velcro / velcro like cabling straps are the simplest most amazing thing I've ever used, really tidy's things up, keeps it looking "Wife approved"
I also second using the shortest cord necessary, but keeping it long enough that you're running w/ the lines of your desk, etc. (nothing worse than a diagnal round of multiple cords shooting across space in a \ line to the power strip). Also, when bundled together, the cords can become quite stiff.
This reminds me, I need to get more of this stuff, I'm down to just a couple unused straps left :)
I think labeling the power cords is a good idea if you have the time, but it's a little overkill in my opinion. I' don't think I've messed w/ power in a LONG time, and I work w/ a popular LAN gaming community so I'm constantly moving my machine. I just have spares, in my kit, so I don't unplug them.