Chain tensioner
 

I already know about the Kore one, but a few years ago I had gotten a hold of ne that clamped to the chainstay and had a plastic roller to it. It was called something like Mr. Dirt, or doctor dirt or something like that, if you can help that would be great, I'm trying to locate one.

Check out Nashbar or Performancebike. They should have that stuff under tools or accessories.