A number of online sites will have useful information. Some of the more relevant and more credible are:
National Archives National History Day Site
Library of Congress Digital Collections
Encyclopedia of Greater Philadelphia
ArchiveGrid -- helps locate archival resources
NJ public libraries have a number of useful databases
Ancestry.com -- most public libraries in New Jersey have a library subscription to this database. It will not include individual family trees or subscriber added resources (family photographs, etc) but it does have census records, birth, marriage, death, and military resources, among others.