Bukkit-plugins is a project mainly written in ..., it's free.
Chack out my plugins :)
Check my plugins :
RC : https://github.com/beatcomet/Bukkit-plugins/tree/RC
Glass Break : https://github.com/beatcomet/Bukkit-plugins/tree/GlassBreak
Fire Tools : https://github.com/beatcomet/Bukkit-plugins/tree/Firetools
Freeze : https://github.com/beatcomet/Bukkit-plugins/tree/Freeze