For information on database services, Commercial Databases.
Not all databases on the Internet require payment for use, though.
There do exist some, largely research-driven databases, which are
publicly accessible. New ones spring up regularly.
To find out more about the databases in this section, contact the
people directly responsible for them. Their areas of concentration
and the software used to implement them are widely disparate, and are
probably beyond the author's expertise. Also, don't forget to check
with your local library---the reference librarian there can provide
information on conventional resources, and possibly even those
available over the Internet (they are becoming more common).