Genie Tyburski recommends on her Virtual Chase blog the "Top 10 Essential Web Sites for Litigators". I am not much of a legal researcher, but I know that when one of the top law librarians points out to essential law sources for research, we need to take a close look.
ZoomInfo, Cornell Legal Information Institute site, GPO Access and BRB Publications web pages have been around for quite a while and they are familiar to most of us.
Somewhat new to me are the Full-text State Statutes and Legislation website for "annotated links to state statutes, constitutions, administrative codes, regulations and city ordinance", Justia with the "federal district court findings database" and the fee based Legal Dockets Online for 'court case dockets, filings, and other public records.'
Anyone doing a basic legal research at your public library will be glad to have these websites, so don’t forget to mention them next time, when you help customers at the reference desk.