http://www.cyclingnews.com/photos/2006/giro06/index.php?id=giro_bikes2/IMG_0520

Redline chain keeper. It's only for 1 1/4" seat tubes, otherwise I'd have it on all my bikes.
$5 from Excel Sports.

the n-gear jumpstop is way better.

That is the deda dog fang, it comes in two sizes.

Yup, that's a Deda Dog Fang...got them on both my bikes. Here's an example (http://www.bikemannetwork.com/biking/p/CH5800).

I recalled seeing one in a shop, at the time he wanted $25 for it, I though he was crazy.

Two votes for the n-gear jumpstop. Only $10 shipped to you (he only asks that you pay after you install it and like it). Comes in all three sizes. I'm up to two now...

www.n-gear.com