Customer Relationship Software has suddenly become inexpensive as it moves to the cloud. One of the beautiful advantages for Saas companies is the certainty of billing which means every user contributes to the overall development effort. (You can't escape the licensing).
Use CRM software to maintain consistent communication with your customers and improve your overall customer service. Your clients will thank you for it. The development of and universal acceptance of the REST API means that new software can integrate with third party software seamlessly so where once producing software like this was not feasible from a coding perspective, now you get the benefit of hundreds of thousands of hours of coding all pulled together into one solution.
Manage your contacts, send personalised newsletters and create a sales funnel to die for with a well organised CRM.