Online Atlas of Victorian and Edwardian population

I think this website Populations past is an interesting source for background information about the places that our ancestors lived.
By hovering over the map you can get thousands of statistics worked out from the 1851 to 1911 censuses at the registration sub-district level. It covers all sort of things, such as population density, illegitimate birth rate, average age at marriage, infant mortality rate, household and age structure, socio-economic status, social class, percentage of women and children working, and for each variable you can choose the year you want (though a lot of the 1871 ones are not yet working).
You can also 'compare side by side', either the figures for different years or the figures for different places.