Ross,
I number my images by using a single letter identifier as to general category followed by the date, image# and location.
Ex.: F20081231 001 BostonMA
Would be the first image (001) shot at a fireground scene (F) on December 31, 2008 (20081231) in Boston (BostonMA).
I break it down further by adding an abbreviated alarm level or incident type and a street address as well. Maybe not the
best but it works for me. Allows me to easily search by type, address, date, city and/or location.
That is of course all done after the fact.
Honestly, I don;t shoot enough images at a scene to make changes in-camera to the image numbering/naming system.
Which now that I rereard your post, was probably what you meant. Eh, poor focus on my part today! hhaha
-Ted