Perth Branch of the Ontario Genealogical Society has a list of Research and Reference Resources by Township pages which appear to be quite comprehensive if the township has been worked on. Most of these references oblige visiting the county or being in touch with the archives or library. They also provide a list of links to various other research organizations in Perth County and beyond.
The Ontario GenWeb Census Project has transcribed the better part of the censuses available (1851-1911) on a township by township basis.
A map of Perth County circa 1951 from Ontario Archives illustrating the townships, towns, villages and hamlets as they were post-WW2 and before the reorganization of the 1970s and later.
