I have never actually been brave enough to go, but I am told the es Firo in Soller is an experience not to be missed. The villagers have their own all day festival in the streets, celebrating and reinacting the Moros y Cristianos.
It is the famous battle between the Moors and the Christians which happened in 1561.
They start at the port in Soller and work their way up to the main square in the town.
I've heard it's as crazy as it is fun and they take their battle very seriously, go if you dare, oh and tell me all about it, I think I'm already busy that day ; )!