Toronto- at About.com
About's Guide for Canada For Visitors has suggestions for visiting Toronto, including family attractions.

Ottawa
Canada for Visitors covers the nation's capital-- a pretty city for visitors. 

Ontario Science Center
Lots of interactivity on this site about Toronto's science playground.

Canada Museum for Children
Though in Quebec, the museum is right across the bridge from capital city Ottawa, Ontario.

Wonderland
Paramount Canada's Wonderland is a popular theme park near Toronto.