S1ru5: The web shape like the comics (which artist by the way? The original Steve Ditkos or later?) would not only look really cool, but give the end of the web a lot of stability. My idea was that the spinneret (if that is the spinny thing on the end that spins the strands together, still really fuzzy on this stuff) would gain speed as the line was shot out. The front of the web line would be spun much more loosely, giving the end a wide cone/web shape (
http://www.youtube.com/watch?v=atCfTRMyjGU, watch the end of the line when it hits the wall at 0:22), and the rest of the line would be spun much faster so as to stay in a line. The problems I see here are that the woven strands could fall apart (this is without the whole charged-threads electrospinning thingy), and the whole line would be ruined, and that the unwoven strands would flail behind the better connected rest of the line, rendering the whole idea useless (this is, however, without testing, so I have yet to confirm either of these things). If these problems do occur, I hope your idea presents a solution to them.
Edit:
Aw, darn it! I suck at computers. Sorry about the weird double post (if it looks weird on your screen).
Edit again: S1ru5, I wasn't planning on retracting the line, if that's what you're getting at. I was thinking you would coat the front of the web (the web being made of the largely non-adhesive dragline silk) with an adhesive as it was shot out, a bladed solenoid would cut the web just behind the nozzle when you released the trigger and you would catch the line, then when you were done let go and that would be the end of it. It would be the spider inspired Oscorp adhesive from the movie, only the real thing. So if my shaky knowledge is right, it's still a polymer extrusion device, since fibroin is definitely comprised of repeating structural units. Bye for now.