To make one of these printers -- Samsung CLP-500, CLP-510; Xerox Phaser 6100 -- work in 10.5, install the August 2007 printer driver [5MB download]. Unfortunately, one library from Tiger that this driver needs went away, so using your Tiger backup disk, do this:

$ sudo cp -i /Volumes/tiger_disk_name/usr/X11R6/lib/libexpat.0.dylib /usr/X11R6/lib

Now install the printer like you normally would (e.g., as a Bonjour Printer). Select the CLP-510 driver, and you're done.