This has probably been posted in the forum in the past but it is good enough to deserve a repost. Lots of good stuff here: http://artoftherifle.com/ (http://artoftherifle.com/)
And ole rifleslinger is a joy to shoot too.
The author is a great guy and a very thoughtful marksman, as well as a former Appleseeder. His slings are excellent. I use one on my AR. Unlike other nylon materials, his are made from a coarse weave that holds tightly onto the arm without slipping, and unlike cotton web slings, they dry really fast.