I'm working on an Android app. We have some flat mocks but I want to get them onto some Android devices to see how they feel and test out flows, labels and copy with people.
In the past on iphone I've used Prototypes by Duncan Wilcox. It worked pretty well for us. I could upload pngs then add hotspots and basic tranisitions. Once I was happy I uploaded the prototype to Prototypes server, got a key and entered that into the app on my iphone. Hey presto a tappable prototype on my iphone.