The Glamorgan FHS have published a whole range of census transcriptions/indexes e.g 1841, 1851, 1861. They are mainly available for purchase on Glamorgan Family History Society
The UK BMD web site "provides 2556 links to websites that offer on-line transcriptions of UK births, marriages, deaths and censuses. A wide range of other indexes and transcriptions are also available for most counties, these may include parish records, wills, monumental inscriptions etc"
Carry out initial searches on all censuses 1841-1911 on LDS Family Search - using basic data supplied by Find My Past (subscription site) and all follow up searches are directed there
Class List of places appearing in each census year for Glamorgan This relates to the PRO's piece numbers, breaks it down into Registration Districts, Registration Sub Districts, Parishes and Hamlets/Townships.
1881 census place name index for details of 1881 census Registration District overlaps and a census district index
Gibson, J.S.W. and Medlycott, M.T. Local Census Listings 1522-1930 (2nd ed.), Birmingham, Fed. of Fam. Hist. Soc. (1994) 52 pp. [ISBN 1-872094-75-9].