I upgraded SkeletonTest in spine-libgdx, making it a nice tool for trying out skeletons. 🙂
It can even load a skeleton without image files, which is what I use when you guys send me only skeleton files.
Maybe I should put a JAR somewhere so people can use it to better understand the runtimes and to try their skeleton files out? It could even be a webpage via GWT, though I probably don't have time to figure out libgdx+GWT. Edit: Get it here. It runs on Windows, Mac, and Linux.