Martha Stewart was the reigning queen of picture rails:
But Phoebe Howard is making a move. Look at all this picture rail goodness. No moulding necessary.
{PS If you're not already, you should be following the updates on Phoebe's stores and recent client work here.}
I'm thinking of taking a trip to HD's plumbing department to see what I can scrounge up for a brass picture rail on the cheap. For those of you not interested in a DIY version, there are companies online that sell the hardware for picture rails ready made.