Here's how to simply use the FireWire 400 hub in your 30" Cinema Display (DVI) with the dual-link adaptor, without the massive nest of unused cable just so the FireWire from the display can reach your computer.
You've upgraded to a new machine with a Mini DisplayPort, and want to keep using your dual-link DVI display. The cable is rather long, and includes USB, but no FireWire. You could try to plug the FireWire into your machine, but the slack they give you is so little, you get a nest from the coiled dual-link adaptor. And its even more awkward if you use a 400-800 adaptor stub.
Here's what I did. Get a normal male-male FireWire cable (800-to-400 if your machine has an 800 port), and just plug it into the back of your Cinema Display. Now you can still hook up 2 FireWire 400 devices thru the monitor: one using the unused port on the back of the Cinema Display, and one using the unused male connection at the end of the monitor's own cable.
Explanation: the 3 connections to a typical FireWire hub (including the hub in the display) seem to all be the same. The only exception in this case is one is male and the two ports are female. The male connection is provided as a convenience and assumed you'll use that to connect your computer. But you can just as easily use it to connect a device, and connect your computer to one of the other two ports intended for devices. Just get a cable of the appropriate length (same as the cinema display cable + dual link adaptor to be a fully apt length). And save the dangling cable on the end of the display's cable for whatever it can practically reach, and set it next to the dual link adaptor's box.
[crarko adds: I haven't tested this one.]
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