These tiny luminous line locks (.7 gram ea) are just great http://www.cleats.co.uk/browse-by-product/line-lok-guy-runners/cl266-mini-line-lokr-for-1-3mm-lines.html as is ultra light 1.25 high viz spectra cord (available at: http://www.zpacks.com/accessories/spectra_cord.shtml ) which (together) makes for a perfect guy line for a hiking tent/tarp. They glow in the dark so well, you can see them clearly through the material of your tent.
The Clam Cleats are made by these folk: http://www.clamcleat.com/products/cleats-for-1-6mm-rope/cleats-rigged-on-a-rope-24.html who have some other interesting stuff.
Another great product is this luminous guyline which you CAN”T MISS in the dark: http://gossamergear.com/ezc-2-tarp-guyline.html
Both of these products are now available locally (in Oz) from these folk (very fast delivery): http://www.tiergear.com.au/11/online-shop/tarp-guy-lines-ridgelines-and-hardware You would want the CL266 Clam Cleat/Linelok and the Glow Wire.