This Android app lets you classify Galaxy Zoo subjects. It is available in the Google Play Store: https://play.google.com/store/apps/details?id=com.murrayc.galaxyzoo.app . Try beta versions early here: https://play.google.com/apps/testing/com.murrayc.galaxyzoo.app . See also the iPhone app for Galaxy Zoo: https://github.com/murraycu/ios-galaxyzoo/
As requested by https://plus.google.com/100123542880051296706/posts/QJWBWTyLTv5 I translated some of the missing strings to German and also reordered the the file so diffing it with the default strings.xml is simpler.