PA_ B,

If your a handy sort of fellow, you can easily make this homemade rod holder. I've used it along with a fancy Cablas Clamp-On Quick Draw model.
The Cabelas is a great holder and offers more bells and whistles, but for ease of use, quick detachment for portages or to switch mounting sided, this homemade model works great.
Basically a heavy duty caproenter type thermoplastic hand clamp, with a 1 1/2 pvc rod holder. The teeth of the clamp can be wrapped in duct tape or shrink tape and won't mar the canoe.
Here's a pic on photocbucket:   (You need to Login or Register