The Internet Archive provides free access to images of the 1900 census. These are not indexed and cannot be searched by name, but can be browsed by enumeration district.
To determine the correct 1900 census enumeration district for the area you wish to search, try this online tool, Obtaining EDs for the (1900-1940) Census in One Step (Large Cities). This page has links to additional tools to search for the descriptions of enumeration districts in smaller areas.
Some public libraries offer free home access (through their websites) to Heritage Quest, which has searchable images of the 1900 census.
