Yeah, it's very useful for transferring data from one Mac to another - Firewire Target Disk mode. I had a Firewire iSight webcam, gave it to my friend for her iMac. Also for low latency audio & video, it's the best.
my one macmini in fact mostly runs from its firewire. I have three enclosures and they are fast fast fast. USB 2 at 480 gets divided with each device. Firewire is dedicated 400 or 800.