Along the same vein, Andrew Dalke wrote up an interesting series of blog posts benchmarking different implementations of population count (counting the number of set bits in a word):

http://dalkescientific.com/writings/diary/archive/2008/07/03...

http://dalkescientific.com/writings/diary/archive/2008/07/05...

http://dalkescientific.com/writings/diary/archive/2011/11/02...

The Stanford Bit Hacks page linked in the original article is also very interesting reading for folks into this sort of stuff.