Also...there are so so many good ones but I would be amiss if I didn't recommend, for the school-aged crowd, AL SIMMONS, who is one of the most creative and funny guys I've ever seen perform for kids (Ken Whiteley produced his albums):

http://www.alsimmons.com

and also KIRK AND MAGOO (Kirk Elliott and Magoo) who are so down to earth and get the kids involved and dancing and the grownups in stitches and are so darned good at what they do:

http://www.magooman.com/kirkmagoo.htm

~b.w.