Microsoft Dynamics CRM is in the cloud and was built to run happily in a variety of environments. This includes at the Microsoft data center, through a partner hosted offering (including additional bundled in goodies), within your office or even within a footprint managed by your Microsoft partner of choice.
If you are thinking of organizing your contacts, documenting and managing a process, building on or out your network of people and yet you are not really sure if you want to put all the infrastructure in place. You might dip your foot in the water with the cloud.
Did you know that despite the cloud, your data still integrates and can synchronize with Microsoft Outlook running in your office? I am not talking about Export and Import - I am talking about realtime sync (or close to real time sync). You don't have to do anything other than to get the intial configuration right.