Oooh, I like this idea.
Cross Edge (PS3) -Five free dungeon DLCs, with many other free item DLC packs. Close to 30 free pieces of DLC in total I believe.
Hyperdevotion Noire: Goddess Black Heart (PS Vita) -Four free DLC packs for items, weapons, etc.
Hyperdimension Neptunia Re;Birth1 (PS Vita) -Two free item DLC packs good for starting off the game with.
Hyperdimension Neptunia Re;Birth2: Sisters Generation (PS Vita) -Five free DLC packs for items and accessories.
Hyperdimension Neptunia Re;Birth3: V Generation (PS Vita) -Eleven free DLC packs for new characters, items, costumes and more. Most importantly, the original Japanese voices need to be downloaded as a free piece of DLC since it isn't included on the game cartridge.
Hyperdimension Neptunia PP (PS Vita) -Six pieces of DLC, mostly costumes with some accessories as well.
Hyperdimension Neptunia U: Action Unleashed (PS Vita) -Five free pieces of DLC for costumes and weapons.
Hyperdimension Neptunia Victory (PS3) -I don't remember exactly, but I'm pretty sure I remember that there are a few extra dungeon DLCs.