Hear, hear. :-) The best looking gear can look like crap when there's a pile of cabling spaghetti behind it. :-)
Things I have used or am using now...
Zip-ties are a must-have.
PVC is good for fixed raceways, say behind your rack. Easy to cut and drill, lots of room, many types of tubing (elbows, tees, Y's, etc.), easy to connect together, and easy to paint any color you'd like (flat so it hides the surface irregularities).
Short cables. It seems like the simplest thing in the world, but... I hate the fact that it's near impossible for me to find good quality 1-meter RCA cables locally. I also hate the urge at the store to get a longer cable 'just in case' or because 'I might use it elsewhere later, and it might need to be longer...' or because I just bought a new source and forgot to order cables and just can't wait another day to play with the new toy. :-) When I'm not in a hurry, I order cables of the shortest feasible length for the purpose on-line. When you've got four sets of component video cables behind your rack, it's a bummer if they're all six feet or longer. Throw in multichannel analog audio cables and you're asking a lot of your rack in terms of hiding spaghetti. :-)
Split loom is pretty ugly; I prefer the spiral wrap type for anything that doesn't need the protection of split loom (is not in my engine compartment :-)).
Expandable nylon sleeving is nice for cables that need to remain very flexible and are uninterrupted. Bundling together RCA pairs, multchannel audio cables, etc. Comes in a lot of colors so you can color code things. The bummer is that you need a hot knife to cut it w/o fraying, and you usually need to put heatshrink tubing on the ends after installing for the same reason (but electrical tape will work too, it's just a bit uglier). But if you buy the right size, it uses very little space so you can use it in areas where you're concerned about restricting air flow. I use it a lot inside PC cases.
I'm not a fan of velcro ties. The only time I used them was when I was doing live sound engineering, and I only used them to keep cables organized while in transit. Black duct tape is more useful on-site than any quantity of velcro ties. At home I don't like them because they collect dog hair and my dog likes to steal them. :-) The hook part is durable, but I always find that the loop part loses much of its holding power over time, defeating the whole point (reuse). I also don't like the look.
Just about any wood trim can double as raceway for speaker wire. We have decorative oak baseboard in our family room, and it was flat on the back. Nothing the router didn't fix easily. :-)
