OS X Tiger - boot partition resize on G4 Powerbook using target disk mode
You can't resize partitions on 10.4.x Tiger without losing all of your data. After trying iPartition and other solutions, I found that Target Disk Mode and another, newer OS X machine (in my case a hackintosh) allowed me to enlarge it, only needing to run repair on the drive afterword so it'd boot again. I could have also removed the drive from the Powerbook, however that'd be almost more trouble than it's worth (removing a million screws, finding my IDE-to-USB adapter... lazy....)