I am using something else you guys may not know about. It is expensive but a great solution. If you are using a mountain bike this will work for you. There is a company named "White Industries" that makes a rear hub called the "eno". It is an eccentric hub designed for verticle drop outs. When you rotate the hub it moves back and forth like a cam. when you get the desired chain tension you tighten the bolts and it stays like that. You can see it at their website if you google white industries. It costs about 150 dollars but it and the bearings are heavy duty. It's originally designed to convert a mountain bike to a single speed and eliminate the need for a chain tinsioner that you would normally need when you remove the rear derailer.
Here is the link. I bought the one designed to work with disk brakes and mounted the top hatter and sprocket from Kings Sales. This makes an awesome setup!