Using Picasa's public photo galleries, an enterprising Australian couple (Peter and Judith) has set up a sort of shopping site that shows off their wares. PJs Wood-Works Nostalgic Tin Signs has a lot of great old signs (as shown) and the "main store" has many more categories.
I have found it helpful to do the stretching exercises my physical therapist recommends. Do some core strengthening exercises, such as the ones highlighted at The Mayo Clinic. By keeping your core strong, your back won't put itself in a position to cause that sciatica pain you are having.