I wanted to take a look at Firefox’s error page a few minutes ago, so I selected the address bar and hit some random keys. Due to a lack of sleep last night and a day of caffeine, I’d forgotten that if it can’t find a site with a given hostname (and still can’t find one through auto-complete), it automatically does a search for whatever you typed in.
I was rather surprised to see that a search for “klasjdf” turned up 508 hits.
As I think about it, it makes sense. Those letters are 7 of the 8 home keys on the QWERTY keyboard layout, and the eighth is not only a semi-colon, but home to a pinky. A touch typist hitting random keys might be inclined to just hit the ones that are already under his or her fingers. One per finger, leaving out the single non-letter, gets you exactly the 7 that I typed.
As for the letter order, I spot-checked a few permutations, the lowest of which was just 251 for klasdfj. Those with patterns scored higher: 18,400 for alskdjf (alternating left & right, working in from the edges to the center); 99,600 for asdfjkl (left-to-right).
I guess there must just be a lot of people typing random text. Infinite monkeying around, so to speak.