Some of the things I shoot involve the military and other military historical landmarks.

Could Zenfolio add "Military" or "Historical" or something like it into the category section.

Currently, the only category that gets close (sort of) is "Transportation" which you must then go into the other two subcategories to locate.

I too have made a couple suggestions for new keywords to ZF on categories.  I know they are trying to keep keywords to a minimum so they don't get crazy and out of hand, but I also know they are taking all suggestions into consideration.  :)   and I think this would be a good idea.

Thanks!