Microsoft Windows Small Business Server (SBS), now called Windows Server Essentials
From Wikipedia:
Windows Server Essentials, (formerly Windows Small Business Server or SBS) is an integrated server suite from Microsoft designed for running network infrastructure (both intranet management and Internet access) of small and medium enterprises....
It is intended to give small- to medium-sized business the tools to manage their own core business IT functions, for example
- Email (Microsoft Exchange),
- Intranet/Internet applications (Microsoft Internet Information Server, or IIS),
- database management (Microsoft SQL Server),
- and others.
Additional information is available from Microsoft here.