That's where TryStack can come into play. To get going, start by joining the TryStack Facebook group. This is the only down-side to TryStack to my mind. I absolutely *despise* Facebook and everything it stands for. Still, even I managed to reset my long-unused F-Book login to join (they should be rolling out other auth capabilities soon - GitHub is supposed to be next).
Within a day Dan Radez with Red Hat had activated my account, and I was able to spin up a couple of servers and got them routing out to the big bad world. Dan has put together a very easy-to-understand instructional video to help with new users:
I should make clear that this is only a testing environment - as a result, instances only stay live for 24 hours before getting wiped. Still, this is more than enough time to confirm functionality using Keystone before, say, pushing a new feature out to your production system.