Disney's California Adventure...don't miss Soarin' Over California...fantastic and should have been sponsored by United. ;o)
Very little for small fries to do at this park. There's a kiddy crawl and a dopey limo ride that kids meet the hight requirement, but most attractions are geared to adults in this park.
Disney has done away with the Magic Kingdom Club and the Magic Kingdom Club Gold Card (though there may be some cards still valid out there.

They are replacing it with the Disney Club. It's just about the same thing but now everyone has to pay for membership. No more freebies to corporations, etc.