Transit Toronto - a very comprehensive site covering the past and present of the TTC

Alan Gryfe's Canadian Transit Information website - contains a lot of interesting information like fleet rosters with serial numbers for many transit systems across Canada,  and vehicle delivery lists.

Toronto Bus Page by Fred Tang

TTC 1001 Page and TransitHub by Allen Dicion

TransitNow by Jan Boic 

ETS Photo Express by A. Wong

Neil's TTC Route Profiles by Neil Jenkins

Public Transit World by Alex Lee

Bus Drawings and Photos by Peter McLaughlin

Windsor Police and Transit Windsor by Matt Sylvestre

Transit Stop Info by John A. Robb