This "Nitdroid" is a project to port android to the Nokia N900.
To find out uses of android, do research. Everything runs well and is pretty useful and amazing, really. The phone functions are being worked on, and i have heard that it will be fixed in a short amount of time. Android 2.3 Gingerbread is the now the main port and is being rapidly worked on. Next time, do some research i persume you are not a clueless baby since you already have a n900