The M.I.T. (Massachusetts Institute of Technology) has recently published the version 2 of App Inventor, a tool to develop Android apps.
Its official website is http://appinventor.mit.edu/
App Inventor makes easy to develop – with graphical tools – both the GUI and the logic of a mobile app. I really appreciated how fast is to develop even complex applications connecting logic blocks:
The main change in version 2 if that now App Inventor is completely browser-based : it runs in your browser without the need of installing any components on your machine: