Here is a new product from Shomer-Tec that will help you rig those booby traps or just to use as some fine gauge cordage. This is a new kevlar trip line that has a been silicon coated to protect it from sun damage (a common problem with kevlar cordage). It also comes in OD green; a color which I've yet to see on the market.
The standard issue Mil-Spec trip wire (shown above) has some advantages- they are great for making snares and repairing gear. However I don't feel it makes the best "tripwire". I typically would use moss colored mono-filament fishing line over it. The only problem with mono-filament is that on a very sunny day it will give a glare. As you can assume this can be counter-productive with booby traps. I think the matte/OD green color will be an advantage over the the GI tripwire and fishing line applications.
The kevlar trip line is housed on a flexible plastic clam-shell. This keeps the line tangle-free as well as offers rapid deployment. You can use a twig or pencil inserted in the center hole and reel it off as needed. The tensile strength of this line is right at about 60lbs. Other applications for this line would be things like gear repairs, snares, as well as fishing line in a pinch. It retails for $5.