There's several street shows in Universal 6 right now if I recall. Fish Market, Sing It, Beat Builders (probably the best one), Marilyn Monroe, Street Breakz. (that i can recall) as well as Blues Brothers, and the shows at Diagon Alley (Celestina Warbeck and the 2 fountain of fair fortune shows). A Day in the Park with Barney is actually a really good show for younger kids too. (They drop fake leaves during the middle of it, that the kids can keep, and have a neat little young indoor playground next to the show) There's a band that plays in the mornings right by the park entrance as well. Universal is filled with the mini shows.
IOA not as many shows, but there are a few, the 3 potter shows there on that side as well as the short Suess one. Christmas time this year may be different with all the new potter Christmas stuff and all the Grinchmas stuff in Suess.