The champion in returning to the conference marketplace, having participated in every conference, is Globalgenealogy.com
Those with multiple consecutive returns are:
Ancestry.ca
Archive CD Books Canada
Arnprior & McNab/ Braeside Archives
Friends of the City of Ottawa Archives
CHIN Radio 97.9 FM Gaelic Hour
Gatineau Valley Historical Society
George Laidlaw, Author
Gloucester Historical Society
Kyla Ubbink, Book and Paper Conservator
Lanark County Genealogical Society
Moorshead Magazines Ltd. (Family Chronicle and Internet Genealogy)
Ontario Genealogical Society, Ottawa Branch and Region 8
Osgoode Township Historical Society and Museum
Ottawa Stake Family History Center
Patricia J. McGregor Books
Quebec Family History Society
The Bookfinder