In addition to these great classroom jobs, try the following.

Newscaster - reports on current events at class meeting
Pet Caretaker - feeds and takes care of classroom pets
Operator - answers the phone when the teacher is working with small groups or students
Classroom Custodian - erases the board, cleans erasers, waters plants, etc.
Banker - works as the bank teller on shopping days
Cashier - serves customers at the class store on shopping days
Economist - studies consumer behavior on shopping days and gives a market report
Line Leader - leads the class to lunch, specials, assemblies, etc.
Caboose - stands last in line and turns off lights when the class leaves the room
Substitute - performs jobs for absent students

Learn more about my classroom economy here.