Funny you should ask...
The new issue of North American Fisherman has an article on trolling for crappie using a crank bait.
Here are their suggestions: Rapala Shad Rap or Rapala Glass Shad Rap, Salmo Bullhead or Hornet, Bomber Model 'A' , Excaliber Fat-Free Fry, Strike King Pro Model Crank, and Cotton Cordell CC Shad or Grappler Shad Jr. Most of the colors they show are shad or bleeding shad, but also a few firetiger and chart.
My husband has used a method on Crappie Killer's (?) website where he uses the Rapala Shad Rap at the end of his long line to set depth and ties a small jig to a couple of feet of line attached to the rear split ring.
He has since switched to trolling (we don't do it much) with a Mepps in-line spinner. - Roberta
"Anglers are born honest,
but they get over it." - Ed Zern