So... I've always tied my guylines onto my tarps with strong knots and left them there. I was thinking of how to rig up my new poncho tarp. Obviously the guylines can't stay on the tarp all the time. I'd want an easy knot that I could un-do quickly. Then it hit me: just tie loops at the ends of the individual guylines, and do a loop to loop connection to the tarp. This is a flyfishing knot, but it's strong, and I think it should work fine with tarps. Here's a link to what I'm talking about: http://www.flyfishingjacksonhole.com/library/loop-to-loop_connection.htm
Anyone else figured this out, or have any thoughts on it?