I've been lusting for Lee Valley Wonderdogs for a while, but I couldn't justify the cost.
After far too long thinking about them, I made my own version with some scrap:
-scrap cherryphoto 2.jpg
-threaded 1/4 rod
-Lee Valley speed knob
-3/4" oak dowel
-nut
I call this the Wonder Mongrel as a tribute to lee valley's tool team. It's a bit uglier, but it works very well---it acts like a quick release version of the Wonderdogs.