I've been in a couple of internet relationships and always insisted that the subbie NOT get a cam. Cam images can be captured and distributed far too easily. As far as photos - I have exchanged a couple of perfectly vanilla pics as it is nice to have an image in mind when communicating, although it is far from essential.

One thing that I did like to use though was internet phone (voice chat). This was mainly because of my particular kink - orgasm tease and denial. Listening to a subbie moan, beg, whimper and struggle is huge turn on for me.