I have really big bookshelves, the kind you order from office max that have like five shelves, each shelf big enough to hold a full sized rulebook or module, and a few even taller than that.
I store all of my gaming stuff on such shelves - it takes two full ones to hold it all now. D&D Core stuff, plus FR, plus Ravenloft fills one whole shelf.
Basic D&D plus miscellaneous 2E modules and such fill another shelf.
1e and 2e hardcover rulebooks and all 1E modules and such fill another shelf.
Shadowrun fills a whole shelf.
Part of a shelf has miscellaneous other games.
Then I have almost three full shelves of Dragon magazine (every issue) and almost one full shelf of Dungeon (every one). With the new format since 3E, the spines are now all square and so they actually fit on the shelf nice and are easy to reference. (The earlier issues have thicker spines than ends, so they don't always go on the shelf very evenly - i had to take the middle bunch of them and put them in spine back - which isn't too big a deal since there isn't anything to see on the spines anyway.