well, there's no kids mentalism because the explanation and for something to happen takes time, and kids want to see something visual and exciting, which mentalism doesn't have.
mentalism on stage has some great effects, u can start with simple card tricks, and yes, cards work ON stage! i can give u a list of million tricks that can be done on stage, u can get some at penguin even... there's an instant download called "a sucker is born every minute", which is a great effect for stage. and like someone else said, max maven and osterlind r both great mentalists, which their dvd's r a must have for any magician, mentalist or no mentalist! i can promise u that u'll use many of the effects from those dvd's sets.
there r also many great books about mentalism, u can get some banacheck books, like PK thoughts (which is sold here at penguin) and go onto derren brown effects, which r usally harder to pull off, coz it usally involves some sleight of hand/sleight of mind.
i found an old osterlind book, don't remember it's name right now, but there's only 1 routine there, coz the rest of the book exlpains about mentalism itself. the routine is that u ask 20 members at the audiance to each name an object, and another member to write them all down as their named. with NO props, u simply name the 20 objects one after the other, only u go backwords at the list! there r many varietis for this effect, but i find osterlind to do it the best.
just do a search on mentalism books, u would come up with MANY. i would first get some books that explain about the subject, and how to increase the reactions, and how to make the mentalism look as REAL mentalism.
i almost forgot, if ur'e into bending silverware, the the gerry & banacheck dvd with bending silverware. it's an amazing dvd!
hope this helpes u a bit,