Puppies!

 is a perk that is to be added to Fallout 3 with the Broken Steel DLC.

With this perk Dogmeat is reincarnated as a puppy every time he dies and can be added back to your group in certain areas. Article on kotaku.com like [[Vault 101]'s entrance. Dogmeat's puppy seems to be much tougher than the original Dogmeat.