The gallery is at
http://ian.umces.edu/imagelibrary/You will see that only registered users can download the fullsize version.
Here are a list of the features that might be of interest to you.
1) When you go to register you'll notice that I collect the user's country.
2) Notice the 'Most Downloaded' option in the menu. This doesn't list who has downloaded what (I don't think this should ever be presented publicly), but the information is being collected and stored in a new database table, so I can see who has downloaded what.
3) I have also integrated the lightbox mod and made the zip download also only available to registered users.
One of the problems you would find applying my changes is that I have also applied the 'Search Engine Friendly' URL mod, as well as swapping all links over to the PID, rather than the POS and made endless other code changes, including improvements to the SEF mod and the entire search process so they all actually work.
As I said, I will see what I can do about getting together the required changes, but I think I might be beyond making that a viable option as there have been so many other changes to the code. Please don't expect anything anytime soon though. I am still finishing off the upload and automatic thumbnail generation for vector files (SVG, EPS etc) and TIFFs, PSDs etc and movies and so don't really have any spare time at the moment. At least it will give you some ideas on possible options should you decide to try to mod the code yourself.