I think I have seen most of them.
Have you considered emotions? Such as fear, joy, or perhaps another color - like blue - or maybe cool or night or dawn - or candid - or translucent - or body - Gee - sorry you asked?? I don't know - I am sure you will think of something good. I like macro too.
Thanks, Karol, they're all good suggestions! I believe when discussed before that we're sort of 'scared' of using people pictures - as some people might object to having their photos displayed without their consent. But I do like emotions and candid a lot, maybe we'll just bite the bullet one day and go for it!