Some of these have already been mentioned but I thought it would be nice to have them in one place.
1841 Census pay-per-view http://www.britishorigins.com/ Index and original images for the following counties: Cambridgeshire Devon Gloucestershire (includes Bristol).
1851 Census pay-per-view http://www.stepping-stones.co.uk No index! So if searching this census here have lots of time and some nice music playing in the background! I had to look through 200 pages before I found my family. It was worth it though Essex Lancashire London Middlesex Surrey
1861 Census pay-per-view http://www.1837online.com Index and images for the following counties: Kent London Middlesex Surrey Essex
1871-1901 Censuses pay-per-view www.ancestry.co.uk index and images for all counties Free at LDS Family History Centers (in Canada and the US anyway)
Have a free download of 2% sample of 1851 census for each county. I have now got square eyes searching the seemingly endless list for scotland road Liverpool.
Will attempt the salford section tomorrow.
Logged
Callaghan (Ireland,liverpool and st Helens 1840 to 1881.) Scotland (liverpool pre 1860) Kiernan, Ritchie (Ireland, salford), Clarke ,Barton (salford greengates and Harpurhey/blackley up to 1930) griffiths, Robson, (Barton on Irwell, Irlam and West Midlands)