Google Docs

In my opinion, this is one of the most productive tools in the suite of applications Google has to offer. If I was a business owner, I would definitely exploit Google Docs for collaboration with others. Think of it this way, there is no need to buy a Microsoft Office license for every employee you have. All what you need is an internet connection, a Google account and you are ready to create presentations for clients, spreadsheets for your budget and word documents to write letters.
What is even better is that with one click, you can share a specific document with anyone you want. Also, the privacy features are very easy to use, just decide whether the person who is receiving the document can only view it or edit it. Overall, Google Docs is a very productive, cost effective and easy to use tool. As a business, that is all what you need!