As we know, Android is open source mobile operating system developed by google. And Its all versions
Honeycomb(Android 3.0-Tablet Version) are fully open source.
Lets see some its most famous forks(derived versions of android)
It is very famous among all android forks and it is built on android 2.3.5(Gingerbread).It provides many functionality which is not available in original android versions. This custom ROM has largest installation in world after original android.
its totally iOS experience android fork developed by CHINISE community and based on same ginger bread.It is very attractive and has more user friendly UI. It has some own applications like own music player,dialer,contacs,etc.
3.Baidu Yi (Chinese: literally “Baidu Yi Platform”, meaning”change” or “easy”)
It is an operating system for mobile devices. It is based on Google’s Android but is a fork by Baidu, the dominant search engine operator in China. It was announced on 2 September 2011 at the 2011 Baidu Technology Innovation Conference in Beijing. So far it is a vaporware, and you can’t see any progress or updates on their website.