Get hold of the Jim Kweskin Jug Band's first record. Geoff Mudaur plays some fantastic washboard, as well as being my favourite blues singer.

Check out Washboard Hank from peterborough, Ontario. He used to play with Fred J. Eaglesmith and is on some of his records, but he has records of his own. Washboard Boogie is a good tune. Google "Washboard Hank" on images to get a look at his rig. He also plays a Falopian Tuba made of PVC pipe and a kitchen sink. He calls it Canada's indiginous musical instrument.

Also check out Teilhard Frost of Flapjack (I hope I spelled your name correctly Teilhard) He uses the wallnut shells suggested by WYSIWYG a few posts back.