I'm sure I haven't even scratched the surface,but two sites I've found helpful are Deve's and Tim Clederman's. I know there are many out there I haven't found yet and I haven't nailed the link business yet so can't stick them in, but if you click on their usernames you can navigate there.
Good luck !
Seeing as you have a 51, be sure to check 'Dad's 50'. He has hundreds of excellent photos, sure they can be of help to you.
