For whom are you looking?
FamilySearch.org, the LDS site, is free and includes the 1880 US Census. By Googling "1930 census" you can get Ancestry databases of many US censuses. All of the information is included for 1900, and some of the others show households.
On the RootsWeb page, you can click Family Trees in the strip at the top of the home page. On the next page, click Advanced Search on the left. That information has been donated and is free.