Windstream recently introduced a great bundled hosted phone system that includes all of the features of an enterprise PBX for a fraction of the cost. This is an excellent product for small to medium businesses. It also includes all of your voice and data services in the package so businesses have ONE provider to handle their services and phone equipment needs.
Check out the below link for a demo of some of the features. The Toolbar is the most unique feature that integrates with Outlook and your Web Browser.