The ceramic rods like the Idahone do "sharpen" a knife in so much as since they're ceramic, they are able to abrade the steel and remove steel to refine the edge....but they're not really meant to sharpen a knife. It would take exceedingly forever to sharpen a knife with one. Now, if you keep the knife sharp, a ceramic hone can extend the time between true sharpenings if you use it regularly.
Or, you can just use a strop (stropping on a stone works well too).
A double sided stone like Mark showed is a good "all in one"....as is something like the EdgePro:http://www.chefknivestogo.com/edgeproapex1.html