Since two days I have been working on a small project called Fangorn (Treebeard from the Lord of the Rings), an application that lets you create to-do lists in a tree manner. You can add task descriptions, images, and subtasks with different importance to the main task. How much of the main task is done will be calculated automatically.
Here is a link to the app on Play Store. There are still many things to do, but I think it's already usable as long as you are OK with unstable software. After some code cleaning I am going to publish it as an open-source application, but right now I am ashamed of my code.
Fangorn is written in Python using Kivy. Hell yes, android without Java. (If you like, you can read my poem "Java, why I hate you"). If you are interested in contributing, any kind of help is welcome. (Installing and telling me if you liked is contribution too! I need feedback, as my only testing device is a Nexus 7, so I have no idea whether it works properly on smaller screens.) Just let me know.
A screenshot of Fangorn:
That's all for now, I need to code on! Stay in "touch", updates including desktop client, sync, and task sharing with friends are coming soon.