Get ready to smile.
3. Storage Spaces
The v1 version of Windows Home Server had an awesome feature called Drive Extender that could pool all your physical storage into one giant drive. It was great, so naturally Microsoft killed it in Windows Home Server 2011.
Although Storage Spaces isn't a technical descendant, it's pretty much back and better than ever! Connect a bunch of internal and/or external storage drives to your computer, and Storage Spaces can merge them into one giant drive - complete with data mirroring and provisioning. You can't boot from a Storage Space (unfortunately), but it's perfect for everything but your system disk.