The CAFTek disc storage unit:
This puppy is the cat's ass. 150 discs per unit. I own four five six seven of them.
It's also distributed by DACAL and Ziotek, just different brand names. The ITech site, which carries CAFTek, is here.
A cool database program controls everything. I have a 'Movies' category and a bunch of sub-categories ("Action", "Comedy", etc), a 'Music' category ("Hard Rock", "Soft Rock", etc), and a 'Software" category ("Apps", "Backup", etc). You find the disc you want, select 'Eject', the unit spins around and out it slides. The program then lists the disc in its "Discs Currently Out" box. You can also manually punch in the slot number on the unit, itself. It'll print out the database in either regular text or Excel format.
There are (at least) three different companies out there selling their own databases to go with the CAFTek units. I thought the ITech stuff was much better than the others and went with that.
Update: This was before the fabulous Movie Collector program became carousel-compliant. More info below.
They're roughly $130 apiece, which I think is a pretty reasonable price. I have mine stacked up to the left of my computer table within easy reach. I've had them for years and haven't had a single problem with either the units or the software.
Hookup is via USB. They piggyback from each other, so you end up only using a few USB slots on your computer. They also have a lockable sliding door on them to keep out house dust — and prying little fingers.
Here's a page with some setup tips. For the tops in movie databases, check out Movie Collector.