Hope some people write here some alternatives, i always watch for good tools too. Most of the documentation tools document the code itself (like JSDoc), but i did not found many for RESTful Api documentation, thats why i start the project :)
One such tool is Swagger [1]. The nice thing about it is that it can automatically write you a client as well. There are client implementations for many programming languages, such as Java, Scala, Clojure, Ruby, Python, PHP, Javascript and C#.