What about an Android app?
We hope to have an app available for Android in the future, and we're tracking requests for it here: http://superbetter.uservoice.com/forums/119811-superbetter-feedback/suggestions/2743363-android-app-or-mobile-web-view-.
We'd love it if you could take a minute to add your vote to that page, and we'll update it to notify everyone when the app is ready. (However, at this time, we don't have an estimate on when that will be.) Thanks!
In the meantime, you can use our full web version at http://superbetter.com .