Just about any printer works well with OSX and Linux these days, thanks to CUPS. But I'd still avoid Canon -- they're a bit of a laggard for that.

To guarantee universal compatibility, get a printer with a built-in Postscript engine, as opposed to one that does it in software. But there are lots of good printers without that too.

For a CHEAP laser printer, look at Brother (OS9, OSX, Linux, and MS) -- they have networked mono printers for well under $100 around here, and colour ones at just over $100. Edit: I got a Brother mono laser for my mother-in-law six years ago, and it's still going strong with no complaints, first on MacOS9, now on Linux.

I recently purchased a cheap Samsung colour laser printer, the CLP-365. Those also retail around here for just over $100 "on sale". The CLP-365W is the same machine, plus ethernet and Wifi. The CX-3305FW is the all-on-one version of the CLP-365W. All three use the same expensive consumables, but for a low use situation that shouldn't really matter.

All of the above models, except the CLP-365, have ethernet, and the Samsungs have Wifi as well. I strongly suggest getting a printer with built-in networking. So.. why did I purchase a non-networked CLP-365? Purely for the toner cartridges and other spare parts, to use in my CLX-3305FW.

Cheers