Let's face it, some game boxes hold a lot more air than game. One of the more extreme examples for me is Augustus. Definitely a game that I want to keep but it took up a fraction of its Ticket to Ride-sized box. It now shares a box with Blue Moon City and Paris Connections. Three games I know I want to keep on playing that take up a third the storage space.
The downside is that I have to consult a chart to find some game :D
The single biggest boon was buying a couple of cases of photo boxes. Carrie originally for me as a storage solution for Dominion but Dominion spread out over a whole bunch of little boxes proved to be a logistical pain. However, each individual box works just fine for individual games. You know, as long as they can fit.
Which is a surprising number of games, quite frankly. I've filled two cases with games, which has made for a dandy storage solution, not to mention a fairly portable game library. Although, at the moment, my plastic case of Pack O Game games has been my traveling library, since it'll fit in a large pocket.
Of course, a side effect of this is I have to be careful where I store these games. Condensing makes the boxes a lot heavier!