Comment Food ties (Score 1) 374
I've done quite a lot of work on an aerodynamic experiment rig recently and found that cheap food ties (the sort you get for doing up sandwich bags) work great for keeping cables together and are a lot cheaper and less permanent than cable ties; sure they're not great for heavy loads, but most of the time they keep things neat.
Also learn to coil cables properly: http://www.youtube.com/watch?v=lLwwB29uQRg; you're not always going to have cables that are properly cut to length and using this method allows you to coil cables in the centre of the cable if necessary without causing extra twisting or tangles in the cables.