I've got to pull six or so lines through the rafters of this building. There's a mess of wire up there, and I'd like to keep these lines separated a bit.
Are there any cable guides that could be quickly nailed or fastened to roof trusses for this sort of thing? Preferably something that cable can slide through during installation.
One easy thing to do would be to just get some 1" or 1.5" flexible plastic conduit and fasten it to the rafters with pipe hangers. This way, you only need to go into the attic once (to install the conduit). All subsequent cable runs can just be fished through the conduit. This type of conduit is readily available at the big box home improvement stores.
I don't have enough points to comment yet, but I'd like to add the tip of pulling some fishing lines through the conduits to help pull cables at a later date - in my experience, cables have a tendancy to get caught on the ridges in flexible conduit.
Being able to tie a new cable to some fishing line, then go to the other end of the conduit and pull the cable through is a big time saver. When you pull a new cable, tie some fishing line to that, so it leaves a new line for the next cable, and so on.
You could use cable ties. Tie the wires together every so often. This would be easier than conduit. You can use a second cable tie to tie the first to something such as a nail in the rafters.