Supreme Court Cases: Web Sources

United States Supreme Court Website
This is the Supreme Court's official website. It includes opinions in PDF format starting in 1991. 

FindLaw
FindLaw's searchable database of the Supreme Court decisions since 1893 (U.S. Supreme Court Decisions: U.S. Reports vol. 150). Browsable by year and U.S. Reports volume number, and searchable by citation, case title and full text. Free.      

Justia
Justia has Supreme Court cases from 1759 to the present. They are full-text searchable, although they are not searchable by field. You may also browse by year and volume. 

LII: Cornell Legal Information Institute 
The Legal Information Institute at the Cornell Law Library offers all Supreme Court opinions from May 1993 (plus some earlier notable opinions). In addition to full-text searching, you may browse the opinions by subject, author, and party.

The Public Library of Law
PLoL aggregates primary legal materials that are available on the internet. The site is free, but it does require registration. It includes Supreme Court cases from the beginning, which may be searched by case name, citation, docket number, and full text. PLoL was created by and is sponsored by FastCase, a commercial database of legal information. FastCase is often available as a member benefit from state bar associations, including Maryland.