I don't know if they still do but Butch and Denny's bait store used to offer a perch caller made out of a pc of pipe a couple of washers and a solid rod. It works similar to the ebijack method described in his post.

Still another method used by the Oldtimers in the fifties was to take a 1 gallon clear glass water/cider jug and place a few live minnows in it with clear clean water and let it to the bottom, they claimed that it teased the perch into a feeding frenzy and kept them from wandering off. Does this work? I have no idea! But it does sound feasible. I remember one old gentleman who used jugs off both back corners of his boat.