I see your reflective guy line, and I raise you *fluorescent* reflective guy line:

http://www.cleats.co.uk/home/details.asp?id=27

Those guys also sell some funky rope cleats that are supposed to be particularly useful.

I bought a pack of 4 pieces (3m, or 9ft each). One piece will be for the front guy line on my tent, two are spare, and the last I cut into 13cm (5") pieces to make highly visible zipper pulls on my backpack.

A