I have a PowerBook G4 that was at one point a daily driver, plus an eMac that was running at one point but needs a new hard drive; those were/are both in desktop roles. I also have a Power Mac G5 and an XServe G5 in server roles. All of them have OpenBSD 5.9 installed (except the eMac, which had OpenBSD 6.0 installed before the hard drive failed).
The XServe and Power Mac are in storage right now, but I'd like to get the Powerbook upgraded to 6.1 eventually (I want to stick full-disk encryption on it, too, so I'll probably just blow away the existing install and start from scratch).
6.1 for macppc doesn't ship with any web browsers except for text-based and Netsurf sadly. It struggled on my 1Ghz iBook speed wise too. I am going to give it a fresh look on a DP 1Ghz Quicksilver too.