For Geeklog users that have implemented gallery as their photo management tool - this may be of interest.
The developer of Gallery (Bharat Mediratta) developed a RandomPhoto function and Nuke family portal block. This Random photo function has a number of features that will be of interest.
It uses the Gallery API and Gallery classes
It ignores empty albums
It caches the albums to improve speed
It only viewes public albums
Displays the photo caption in the block
Dispays the album name and link
I have integrated this function now as a Geeklog block function - requried some code to restructured, use geeklog display method and fix a session related problem. Also added a little bit of logic to not display image caption names that are default ones - like your photo ID.
I've archived up the files and instructions and they are available on my site here or at squatty.com