Cyanogen

CyanogenMod is an alternative Android OS distribution

Advantages

 * Built from Android sources : spyware free, NSAware free, ...
 * Rooted
 * Community maintenance for discontinued phones (eg old HTC Hero)
 * Network-friendly options (eg Tethering with SFR, Connection with WiFi Adhoc, ...)

Drawbacks

 * Unsupported cameras
 * Intempestive crashs