Morningstar
Provides stock and fund information allowing you to research current or prospective holdings or see how your investments fit together.

Reference USA
Provides detailed information on more than 12.8 million U.S. businesses and 120 million U.S. residents.

Standard & Poor's
Provides professional analysis and ratings for over 5,000 U.S. companies, 9,700 corporate bonds, and over 14,000 mutual funds.

Value Line
A larg independent provider of investment-related information. Their goal is to provide timely, accurate, and unbiased information in a format that integrates fundamental equity research with quantitative disciplines.