#3 SalesForce.com

Salesforce.com is the enterprise cloud computing company that is the leader in Social Enterprise. Best known for its customer relationship management (CRM) product that helps employees collaborate easily and connect with customers like never before.

In Q4 of 2011 alone, SalesForce.com has processed 45 billion customer transactions and sports 100,000 customers worldwide.

#2 Amazon Web Services

Amazon Web Services (AWS) is a collection of remote computing services, also called as web services that together make up a cloud computing platform, offered over the Internet by Amazon.com. It offers a complete set of infrastructure and application services that enable you to run virtually everything in the cloud be it enterprise, social games or mobile apps.

#1 Google Docs

Google Docs is a free, Web-based office suite and data storage service offered by Google within its Google Drive service. It is now one of the best ways to collaborate, share documents with co-workers and store business information in the cloud.

This means that there's no need to download and install software on a particular machine, any cloud connected computer can access Google Docs. And multiple users can make edits to the same files at the same time, it’s called online collaboration, and it could streamline teamwork over the Web. And another advantage is that Google Docs preserves earlier versions of documents, so no need to get fuzzy over the undesirable changes made in file.