Hi,
I recently bought the stretching pliers recommended here (another thread under this section) and I LOVE them! They are so much easier to get a successful stretch job done, and it takes less strength to tighten the canvas thanks to a bar they add to the pliers which increase one's leverage.
I highly recommend them over what is available at the local art store.
here's the link
http://www.midcoast.com/~twnbrook/tbplier.html