I do put link up to the root & a bullshit links page on each one, but that's on the bottom in the copywrite area, so it's mostly for SE's & sees very little traffic.
I have seen (and used to to this back in the day) ads on the last gallery page that went to a click thu or top list or free email thingy - sort of a last ditch effort to squeeze whatever you can out of your traffic.
The main goal should be to sell the sponsor
