Grapple Guns

I really want a grapple gun! In my earlier robot arms post (you should check out the link at the bottom if you haven't read it), I mentioned a desire for a grappling cable launcher built into robot arms, but I've changed my mind. A pistol that fires a grappling line would be so much cooler. Rorschach from Alan Moore's Watchmen has a pretty cool one. Nightowl made it, but I don't think he made himself one. I wonder why not? Batman also has a few cool ones. I like the Dark Knight and Arkham games' versions the best. I like the batclaw because you can also use it to grab people and stuff.
http://geniusideasandstuffiwant.blogspot.com/2011/09/robot-arms.html