Create a IDE ("light version of eclipse") for Android tablets.
The IDE should be extendable and modular.
The best use case is for tablets like Asus Transformer Prime
Basics:
Syntax Highlighting
code completion
Light UI
Gesture Controlling (Slide, ..?)
...
Modules:
HTML / Javascript / CSS Module :
very easy to implement. Use build-in Browser for execution.
C / C++ Module: Usage of NDK ...
GWT Module: GWT compiler is open source
Java: Is there a java compiler?
Ruby: it's possible to run ruby on rails on android
...
Some more ideas:
Integration of GIT (GitHub)
Cloud compiling
Cloud prject hosting
Cloud testing (CI, Jenkins etc.)