How to use picture sharing sites?

In my bookmarking campaigns I've used a tool that created accounts on a bunch of picture sharing websites, like:

Blipfoto
Dropshots
Fotki
Fototime
Imageshack
Mobypicture
Photobox
Photobucket
Shutterfly
SlideShare
Snapfish
Webshots

I'd love to know how to use them to the full potential, any info would be valuable, it doesn't matter if it's black, grey, white or purple hat. For some really nice or sneaky ideas I'm willing to share some of my accounts