Can anyone ever really have too much Munchkin? I don't really think so. But that's me. The folks over at Steve Jackson Games also don't think you can have too much Munchkin. As such, they've got two new expansions available.
Munchkin 6.5 - Terrible Tombs is meant to be added on to Demented Dungeons (or any other expansion that uses Dungeon cards). This set gives you 20 more Dungeons to search around in, as well as 16 new Portals with which to get you there. Meanwhile, Munchkin Knights adds 15 more cards to your game, obviously with a knightly theme to them. Steeds, swords, and dragons await.
Terrible Tombs Source