Hi, Festivals I like in Ontario are:
Mill Race - Cambridge Ontario - long weekend beginning of August - Brad McKewan does a great job!
Home Counties in London Ontario - possibly best one I've been to re. crafts
Celtic Festival at Goderich has already been mentioned.
Of course there's lots of others - can probably get details via Northern Journey Online -
http://www.NorthernJourney.com/
or one called UFOJOE - who's URL I can't remember - listed in NJO, however.
Rana