Pros -- Roddick has been wearing ASO braces on both ankles for years. I think I spotted Isner wearing them as well at the Sony Ericsson.
Personal -- I've been wearing an ASO brace on my left ankle for years. I turned my ankle and, since then, it's been notably weaker in stability. The ASO brace provides just enough support to avoid re-injury, but I have a full range of motion.
TW sells one model here --
A teammate of mine has a similar model, but her brace (given to her by her doctor) has removable plastic shims. The shims provide additional support, at the cost of reduced range of motion.