One of my local airports, Philadelphia International is apparently the first airport in the country to get a new virtual fitting room, supplied by Intellifit. A couple Levi's stores already have similar machines.
So how does it work? Basically you stand in a kiosk that's 7 feet in diameter and 8 feet high while a machine probes... err... scans you and collects 200,000 data points. That information is compared with the measurements of brand-name clothing in a database. Now you can buy clothes from those companies online without having to worry about whether they'll fit.
There's not a huge selection of clothing brands in the database at the moment. Currently you can shop for Nordstrom, Levi's, Lands' End, GAP, Natuica, Dockers, and Jos. A. Bank.
Now, maybe it's just me, but wouldn't it be easier if the measurements were just a bit more standard across different name brands? Then all you'd have to do is shop by size. Of course, this is coming from a short guy who can almost never find jeans on the shelf that will fit without cuffing the legs a bit.