I built shelves that hold about 6 deep. I made them approximately wide enough to hold a full batch on each shelf. I have 4 shelves of space available, and have a tag on each with the beer type on it. The tag just hangs from a nail - nothing elegant (upgrading that is a someday project).
It's a great theory, but in practice, it doesnt work so well. I have one shelf right now that's dedicated to miscellaneous - both leftovers from previous batches, bottles from mini (1-2 gallon) experiments, and a few commercials. Luckily, I have a freezer set to be delivered on Monday, which will hold kegs, and so the shelving system will be only for long-term agers, bottles for share, or commercial beers. I'd like a better labeling system, but it works. And since the shelves hold six bottles, a six pack takes up a row, making it a little easier to know what's on hand.
Hope that made sense. I'm sleepy and filled with cold medicine.