I really like the Storage Spaces feature of Server 2012 (click to read more and a small overview of the technology), currently still in beta. It is one of the major reasons that I will be upgrading from Server 2008R2. I originally have Home Server and loved it, but the loss of the drive pool feature in the newer version of the Home Server software dropped it. There are several third party options, but I went to the larger version of the server software. Now, it looks like they are bringing that functionality to the full server installs.
Storage Spaces is a feature that takes standard JBODs (Just a Bunch of Disks) connected to a Windows 8 Server and allows them to be used to create pools of storage. The pools can then be used to create volumes on the server. The benefit of using Storage Spaces is that it enables advanced features such as resiliency and space optimisation. It also forms a basis for using directly connected disks with the Windows hypervisor, Hyper-V. The concept of Storage Spaces is not new. Many operating systems have logical volume managers (LVMs) and in fact, Windows already offers some volume management features. Disks can be partitioned and recombined to create mirrored and parity protected RAID volumes. However storage spaces does things differently using disk pools, which provides significant advances over the disk management functions available today.