If you break the word down, you'll see that "kiri" is the Japanese way of saying "kilo"--the metric word for 1000. "ban," when using the kanji 番, is the Japanese word for "number."
Therefore, it's the thousandth number, and is generally used as a view counts landmark.
Thanks, everyone!! 5000 kiriban! ZOMG i'm sooo happy! TT~TT
15,000 kiriban contest! Send me a pic of my pageviews at 15,000 pageviews and I'll send you a prize!!