Alright, here's the story:
After a week-and-a-half in Yosemite, Matt and I were feeling spritely so we decided to try Half Dome in a day. We hike up there in the wee hours of the morning and rack up at the base and pretty much hit it. After about an hour I started off leading the fourth pitch--a short 5.11 bit to a bolt ladder then a 5.9 thin-hands crack. I got up to the 5.9 hands part without incident and got situated. The climbing was really tenuous (much harder than any of the 5.10's we did that month, actually!). After about five feet I put in a cam and clipped it. Just as I did that, I believe one of my feet skated and I was off. I'm not entirely certain how everything occurred, because it happened quick. All of a sudden I was off and then a couple of feet later I was at the end of the rope. No big deal. I grabbed the line to batman back to the piece and get moving, but I saw my finger and stopped. "Holy f***!" was my immediate thought, if I recall correctly. After a few seconds of analysis, I realized that, yup, I wasn't going to be able to climb. I lowered off and Matt cleaned the stuff then lowered off a bolt on the ladder. We then rapped off and hiked out. I ended up with 14 stitches, reattaching all the flesh that was hanging off. The doctor did a fantastic job--we ended up climbing the Nose three days later (with the stitches in!).

As for exactly how the injury occurred, I believe that my finger must have caught in the rope as I fell (I had just placed the cam, remember). As I went past, the rope would have pulled my unfortunate digit up and into the carabiner on the cam, pinching the end and ultimately tearing it off. It seems to be the only reasonable way that it could have happened.

So, anyway, the lesson here is: "Don't grab the rope, kids!"

Either that or just have better luck. You take falls like that all the time sport climbing, generally without more...

Lambone, yeah, it was Matt and I. As for the pain tolerance bit, I whined like a constipated mule the entire way up! Actually, it wasn't so bad except when I got my stitched up finger stuck between my jumar and an edge. I thought I was going to puke it was so painful. Matt did all the hard work anyway -- I was just along for the ride.