Here is American Sport Jujitsu:
SJJ has a number of rulesets but the most popular can be seen on Wikipedia under the IJJF page. Also the amount of contact aloud varies with Black Belt and Military competitions ghaving full contact varients.
I've competed under the IJJF and BJJAGB rules with the main difference being the BJJAGB have one minute stand-up, one minute grappleing and if the match has not gone to the floor then one minute ground fighting. It's fun but the free flowing nature of the IJJF rules are much better.
I train with Prof Martin Rogers and compete under him in SJJ at the Budokan and can testify that its a great place to train wether you want to learn Kempo Jui-Jutsu, BJJ, Kickboxing or MMA. It has a great spirit with everyone working hard towards there goals with great instuctors to help you along the way.
The dojo trains there SJJ and MMA fighters alongside each other with techniques being tweaked for the competitor for there rule set and also ability. This shows the similarity in skills and the adaptability between the two.
I personally have always thought of SJJ as a tamer version of MMA with more emphasis on using throws as opposed to takedowns. The phases could be summed up as kickboxing until a grip is taken then it becomes a judo match with striking suspended until the grip is broken. It a fun way to pressure test your techniques as all those who do judo can testify whilst allowing for the entry techniques and striking you would expect in Jui-Justu. I love it and would suggest it is a good starting point for anyone looking to compete in martial arts.