Vale Tudo means "anything goes" in Portugese. There are still rules, but not as many as the current UFC. Last I checked there were no weight classes in the Brazilian events, and the rules were similar to early UFC's. Japan and Europe also held some famous Vale Tudo events. Some of the Japanese ones from the mid 90's featured Rickson Gracie. The early European ones also had some great UFC fighters participating (Taktarov?). The early Brazilian ones had a lot of Vanderlei Silva. I've lost track of the recent ones though, but if you can get your hands on some of the old event tapes they are worth watching.
http://www.europeanvaletudo.com/default.asp
http://www.valetudo.com.br/
