Pubmed: professional free medical database of the National Library of Medicine. Used by physicians and those doing extensive research on a health topic.

Medline Plus: The health database for consumers with full explanations of countless health topics. This database is a good place to begin research on a health topic.

Practice Tests for almost every occupation! Learning Express asks you to register, which allows you to save your work and continue where you left off.

A very large list by subject of free databases for information on almost everything. 

Infohio provides access to the PV Middle School Library Catalog. You can search it here through Andover Public Library's Web Page.

Here is a dynamic on line encyclopedia and so much more for school and just to learn.