SCA
Society for Creative Anachronism
The SCA is an educational non-profit educational corporation that began in 1966 and now has chapters all over the world.  The SCA promotes the re-creation and study of western medieval history and culture.  The organization holds events (with attendance in the thousands), and offers programs and presentations on all aspects of the middle ages.  My wife and I met in the SCA and I was one of the founding members of the Kingdom of Atenveldt - in 1969.  Today our sons, and the sons and daughters of many of the founders, carry on the traditions - and make some of their own -  of the SCA. 
Marshalling the Women's Tournament.  My lady holds a tournament each year just for women fighters in the SCA, which I help marshal.
Dad, David and John
Having started in the SCA when you had to make everything yourself, I'm always amazed at seeing armor shops at events, that take Visa Cards!
Just one example of the excellent work being done in the SCA.  This was a prize given out at a tournament.
Things you might see at an SCA event.
Balista / Medieval Artillery
The SCA time period is anything "pre 1600 AD."  These are Greek Hoplites going into battle
Drummers at the melee
The SCA is not the Rennaissance Faire - but we have many merchants who sell every aspect of medieval ware.
Knight at the Joust
Knight at the Joust
Medieval crafts of all types.
Exceptional art and craft
single tournament fighting
Pas d Armes field for tournament
Pas d Armes weapons rack
Samuari
Atenveldt - Then and Now