Jewish children have a bar (or bat for a girl) mitzvah at the age of 13 (or 12 for some girls). The religious ceremony is a "coming of age" ritual and traditionally marks the child's entrance into the Jewish community. After the bar/bat mitzvah the child is responsible for keeping (or not) all the rules of Judaism. Although there's no religious reason for the party, it's become a pretty big deal for most Jewish kids!
The party has no religious basis or rules, so it can take many forms. Many people simply celebrate after Saturday services with a luncheon at the synagogue, but many hold big parties on Saturday night or Sunday afternoon. The parties can be small events held in someone's house, or large events held in a "kid friendly" venue such as a bowling alley, or even a hotel. Many bar/mitzvah parties take on elements of a "mini wedding" similar in some ways to the Latin tradition of the quinceañara.
As with weddings, having a "theme" for the bar mitzvah party has become a popular trend with entertainment and decorations planned around the theme. The parties are multi-age events, with the majority of guests being around the age of 13! For this reason, DJs with a wide range of music are the most popular entertainment choice. Because 13 year olds are notoriously shy and awkward about dancing, many people like to hire DJs with a dance team or other entertainment. A great DJ can get even the most awkward adolescent on the floor. Of course, 13 year olds are also extremely hard to please, so it's best to make sure the guest of honor is included in decisions to prevent anyone "lame" from being hired.
Because so many of the guests are so young, a long reception generally needs more than one form of entertainment. Magicians, balloon twisters, stilt walkers, caricature artists and other "strolling" forms of entertainment are good choices for mingling in the crowd, as are more stationary things like face painters, photo booths or even bounce houses for an outdoor event. Make sure that any entertainer you hire is aware of the primary age group of the guests, and of any restrictions. For example, if the reception is being held in a synagogue and he or she won't be able to get in to set up until after the sabbath.
The popularity of bar mitzvah parties means that the stress involved in planning one is high. It doesn't have to be though. Just like with a wedding, it's not about how much you spend, or everything being perfect, it's about celebrating moments and honoring the important people in your life. Are you planning a bar or bat mitzvah? What sorts of things have you seen done?