Not much of a hack or mod, but just easy repurposing. The 6x6 and 6x11 Komplement organizers, usually used for closet organization, just happen to be the right width for putting DVDs in. This provides an easy way to organize your DVDs by shows with multiple sets, multiple seasons, genre, etc. Being cloth, it doesn't take up much space either - the cloth ends of each organizer uses up less than a half of a standard DVD case; use two of 'em side-by-side on a shelf, and you'll only lose about the space of one standard DVD case. An added bonus is that you'll now have "bricks" that can be stacked one upon another (without worrying about DVDs tumbling down), making better use of taller shelves.
These regularly sell in a 6-pack for $8, with 2 of each in 6x6, 6x11, and 11x11.
IKEA | home | Clothes storage | Wardrobes | Interior fittings | KOMPLEMENT interior fixtures | KOMPLEMENT Box, set of 6
You're on your own in figuring out what to do with the remaining 11x11 organizers.