Netgear ReadyNAS RN10221D 2-Bay Network Attached Storage
While there are a number of different models offered by Netgear in their ReadyNAS line, the RN10221D is probably the best option for home use. It gives you a good amount of storage with room to expand without overwhelming the average user with excessive options. This model comes with a 1TB hard drive in each of its two bays but it can support up to 8TB total storage. Although the pre-installed drives don't take full advantage of the storage possibilities with this NAS, they’re a pretty good start at a reasonable price.
This model has 512 MB of memory and a 1.2GHz processor, both of which should be sufficient for a lot of home setups, but would be a poor choice for a large business. You get a single Gigabit LAN port on this model along with an eSATA port for additional external storage, and it has one USB 2.0 port and two USB 3.0 ports.