For my day-to-day communication, I can't shake Outlook. Nor do I want to. Whether I'm working on my PC or on my Mac, Outlook 2010 and Outlook 2011 are fantastic applications that keep my email and calendar in one tidy spot. On my PC, I've also connected Outlook to a number of SharePoint sites I use in my consulting business, so it really is a single point of information management in many ways.
For my own use, I've subscribed to Office 365, which makes Outlook a natural choice. That said, I've relied for years on Outlook to manage my day-to-day. In fact, I generally switch to running beta versions of Office when they're available just because of the enhancements that Microsoft continues to make in Outlook.
Photo credit: Microsoft