[gjm11]

There's a nice discussion of this from Terry Tao (outrageously smart mathematician; has a Fields medal) at http://terrytao.wordpress.com/2009/07/03/benfords-law-zipfs-... which contains, e.g., the following nice observation: if X follows Benford's law and Y is any positive random variable independent of X, then XY also follows Benford's law. (Tao goes a bit further than this and thereby sheds some light on why many things approximately obey Benford's law.)

[EDITED to add: Discussed before on HN: http://news.ycombinator.com/item?id=687241. There have been quite a number of other discussions of Benford's law on HN, too.]