Tom White: "Disks have become tapes"
http://www.lexemetech.com/2008/03/disks-have-become-tapes.html
"In essence MapReduce works by repeatedly sorting and merging data that is streamed to and from disk at the transfer rate of the disk. Contrast this to accessing data from a relational database that operates at the seek rate of the disk"
Cassette Generator
http://www.says-it.com/cassette/index.php
"Keep trading the tapes! Just enter some text and click the 'Go' button. A picture of a cassette will be generated for you."