I have an iMac G3 that does not have a DVD drive, which was gifted to me along with install media for Mac OS 10.0-10.4. When I received it, it had Mac OS 10.4 on it, but I have since wiped the hard drive and am installing my way back up to it (I'm currently on 10.3).
However, I'm not sure how to install Mac OS 10.4 (Tiger) since it comes on a DVD, but this iMac doesn't have a DVD drive. The original owner said something about how they put Tiger on an iPod to install it, but didn't remember the details. I could probably scrounge up an iPod if I need to, but I'd also be interested to know if there are other ways to install Tiger on a Mac without a DVD drive.