Obviously the developers at Blizzard are just as tired of loosing a ton of their bag spaces to keys as we are. Coming in the next patch (1.11) are key rings.

We're pleased to announce that the keyring functionality has been completed and will be in place for patch 1.11. When a player first acquires a key, they will automatically acquire a keyring that will hold permanent dungeon keys. The size of this keyring will increase as the player goes up in level -- as seen below.

Level 1-40 = 4 slots
Level 41-50 = 8 slots
Level 51-60 = 12 slots

You can check out Eyonix’s complete post and comment on it here.