Lately I’ve been dealing with WAN accelerators a lot, with the emphasis on Cisco’s WAAS (some other, smaller players are Riverbed, Juniper, Bluecoat, Tacit/Packeteer and Silverpeak). The premise is simple and compelling: Instead of having all those servers at your edge locations, move your users’ data to the core and make accessing the data feel almost as fast as having it locally, by deploying appliances that act as proxies. At the same time, you will actually decrease the WAN utilization, enabling you to use cheaper pipes, or at least not have to upgrade, where in the past you were planning to anyway.
One subject I keep hearing about is deduplication. The idea being that you save a ton of space since a lot of your computers have identical data.
One way to do it is with an appliance-based solution such as Data Domain. Effectively, they put a little server and a cheap-but-not-cheerful, non-expandable 6TB RAID together, then charge a lot for it, claiming it can hold 90TB or whatever. Use many of them to scale.