OpenBSD on a Sharp Zaurus Linux-based PDA from 2005? Of course, why not?
Installing OpenBSD was easy. The instructions in INSTALL.zaurus are pretty straightforward. My 5.6 install was smooth. Installing sets took ~10-15 minutes. The Microdrive is really slow. I’ll replace it with a CF card soon, which should be slightly faster (and more reliable).
↫ goldfish
Of course, it includes a working X desktop, which is neat and makes the device a lot more useful. I have a slightly older Zaurus PDA, and this post has made me interested in doing something similar to it.

OpenBSD has had Sharp Zaurus support for (or at least development started in 2004 (OpenBSD 3.6)