The Japanese company, Elecom, has announced a new portable CD/DVD destroyer, the SCR-CD001. Powered by the USB bus, the SCR-CD001 will make a disc unreadable in as little as 5 seconds. Here's part of their press release, translated from Japanese:

After the enforcing of the private information protective method, data outflow problem from the personal computer to be good becomes topic, but data outflow is not from just the personal computer. After the using when it cancels that way carelessly, there is a possibility of reading the data with the third party even from the media of CD-R/RW and DVD±R/RW etc which are used for exchanging the data frequently. The fact that data outflow from this kind of disk which is cancelled is prevented is "SCR-CD001". By the fact that damage is done to the data logging aspect of the CD DVD media, reading of the data with CD/DVD drive of marketing is made impossible, outflow of the data is prevented.
Elecom is quick to point out that the SCR-CD001 only makes the disc unreadable and doesn't actually destroy the data. The SCR-CD001 is scheduled to ship at the end of November for 3,150 Yen ($27US). More information can be found here.