Google

Google is the largest and most popular search engine on earth. Google's market capitalization is $197 billion as of February 2011. They offer a wide range of internet services, many for free, including:

Search Engine for all types of internet media
Office Productivity software
Email
Translation Service

They have acquired many companies which has given them access to a large portion of internet traffic, including:

Urchin, now Google Analytics
Blogger
DoubleClick
YouTube
FeedBurner
ReCAPTCHA

Google makes the majority of its revenues from its advertising programs, specifically: