Star, Life, Eagle: Positions of Responsibility
Every Scout needs to serve in a position of responsibility in order to advance past First Class. Some are elected, some are selected, and some are assigned.
Click here for an article in Scouting Magazine that goes into detail and lists all the positions that count. Note that Assistant Patrol Leader doesn't count, while Troop Bugler kind-of counts.
The article also talks about positions of responsibility in Venture crews and Sea Scout ships. One Scoutmaster wrote in to say that he created his own position of "Junior Popcorn Kernel." Sorry, that doesn't count, but another Scoutmaster suggested a creative work-around.