eMarketer
http://www.emarketer.com/
eMarketer is the digital marketing industry’s leading research firm, providing marketers with the most comprehensive view into the state of the digital marketplace.  The site provides internet market statistics, news, and reports.

Interactive Advertising Bureau
http://www.iab.net/
Founded in 1996, the Interactive Advertising Bureau represents over 300 leading interactive companies that actively engage in, and support, the sale of interactive advertising.

iMedia Connection
http://imediaconnection.com/
iMedia Communications, Inc. is a trade publisher and event producer serving interactive media and marketing industries. The company was founded in September  2001 and is a subsidiary of dmg world media.

Snap Surveys
http://www.snapsurveys.com
Formed in 1981, Snap Surveys has established itself as one of the leading specialists in the processing of survey questionnaires. The company is privately owned and funded by its directors and has offices in Bristol and London, England, and Portsmouth, NH, USA.

Forrester Research
http://www.forrester.com/
Forrester Research, Inc. (Nasdaq: FORR) is an independent technology and market research company that provides pragmatic and forward-thinking advice to global leaders in business and technology. For more than 24 years, Forrester has been making leaders successful every day through its proprietary research, consulting, events, and peer-to-peer executive programs.

Internet World Stats
http://www.internetworldstats.com/
Internet World Stats is an online source for current data from more than 233 countries and regions on internet market research data, usage, and population statistics.