put it in your car then

* run tomtom on it (need angstrom)
* attach a large wireless NAS and use it as a media player
* get a data logger interface and log your engine management unit data

or get one of these cameras and use the zaurus to control it:
http://www.32bitimages.com/?p=19

Install one of the X distros (pdaxrom) as a base, then port as much Maemo over to it as you can. I'd love to see maemo running on the Zaurus clamshell models.

Second thing, I found a front-end shoutcast client for the Zaurus on a Japanese site, it's written in ruby. Seems too work fairly good, but some of the buttons and messages are in japanese. It's fairly straight forward though to cut-n-paste them into google translations, to get a rough translation going though.

I too used the shoutcast client on zaurus, was quite useable, was translated to English by someone (forget the name, hermasoft?), but it was a bit ugly.

You could also use an old zaurus as a TCP to serial console driver.

Set up a streaming audio server and use it as part of an alarm system?

Install an x11 distro or one with vnc server, plug zaurus into your hifi, remotely run xmms and then can use it as an internet radio?