There is lots of great information about using exiftool at http://www.sno.phy.queensu.ca/~phil/exiftool/filename.html. The one I use to manage my photos is
exiftool -d %Y/%Y-%m-%d "-directory<datetimeoriginal" ./
Another pattern that I'm trying out, to play a bit nicer with image browsers. Puts all images from the same month into one directory, and prefixes the file name with YmdHMS_ to make sure chronological order is preserved.
exiftool -r -d %Y/%m/%Y%m%d%H%M%S_%%f.%%e "-filename<datetimeoriginal" ./
Another incarnation of the same idea, but with more descriptive month directory. (i.e. 01-January instead of 01)
exiftool -d %Y/%m-%B/%Y%m%d-%H%M%S_%%f.%%e "-filename<datetimeoriginal" ./ exiftool -d %Y/%m-%B/%Y%m%d-%H%M%S_%%f.%%e "-filename<filemodifydate" ./