AngelList
“The world’s largest startup community”: a platform for startups designed to connect with investors and raise money. Gives succinct information about startups, the products or services they offer, and the people trying to launch them. Search its startup database by market, location, stage of funding, total raised, and more.
Corporate Information
Offers free bare-bones reports on companies (meatier profiles are subscriber-based), research links, a list of the top 100 companies worldwide, and a glossary of business definitions.
The Deal
In its efforts to chart “the Deal Economy” this site logs news of mergers and acquisitions, IPOs, bankruptcies, venture capital, and private equity.
FDIC Bank Data and Statistics
Access comprehensive financial & structural information about every FDIC-insured institution.
Google Finance
Stock market quotes, news articles, etc.
Hoover’s
Hoover’s provides information on private and public businesses. Subscription-based, but available free through many libraries.
IndustryWeek: Resources
Resources include the IndustryWeek 1000, IW’s annual ranking of the world’s largest public manufacturers by revenue.
Investor Network (IN)
Offers news and commentary on every industry, as well as information on company earnings events, funds, and conferences.
NVCA
The NVCA (National Venture Capital Association) is “the preeminent trade association” for the US venture capital and startup community. Its research resources offer insights into venture capital fundraising, investment, and exit trends, statistics on human capital in the industry, and analysis of venture activity by geography, sector, stage, size, and other attributes.
OTC Markets
Quotes, stock charts, and company profile information on more than 10,000 companies that might be hard to find elsewhere.
Preqin
Information and articles on private equity, real estate, and hedge fund firms. Most is fee-based, but offers some good free information, including a glossary and some Research/Insights reports and blog posts.
Private Equity International (PEI)
Excellent source for information on private equity and venture capital. Fee-based but often available through university libraries.
Public Register Online
Provides annual reports for approximately 5,000 companies that participate in the service. Requires registration, which is free, but also allows featured companies to send you future correspondence.
TechCrunch
Tera-oodles of information about tech companies and new products. TechCrunch also hosts CrunchBase, a free database of tech companies, entrepreneurs and investors that is open to the public to edit.
VB Profiles
Spoke Networks and VentureBeat combined efforts to establish VB Profiles, which provides business information and aggregates news, mostly for tech companies and their executives. Free registration.
Yahoo! Finance
Provides profiles, news, SEC filings, and executive bios, not to mention the all-important insider holdings and salary reports.