Played a bit with Linux kernel modules. Found out that writing modules for the kernel-space is not hard at all. Wrote a module which creates /proc/foo. Source at strlen.net/foo.c. Thinking of getting more information on how my UPS works and writing a loadable module for that also. kupsd would certainly sound nice. I tried getting data from my UPS (which is connected via a serial port) using minicom, on what is sent to the systems when power is out for example, but no such luck. It's an APC Smart-UPS 420.
Installed OpenBSD on my Sparc. Works well, openssh is very usable. Played a little bit with OpenSSL as well. CVSUP works well under SunOS emulation, with which I've played a while too.