As you would have known if you talked to me about it, I really, really like the Morbid mechanic. Being personally White-centric myself I tried a lot of WB morbid decks, but those just paled in comparison with GB Morbid decks.

Let me list my first deck: the budget version of GB Morbid, and elaborate on all else later.

Green/Black Morbid:

Creatures: 23

Young Wolf x4
Strangleroot Gheist x4
Reaper from the Abyss x1
Vorapede x3
Dawntreader Elk x3
Demonic Taskmaster x2
Demonlord of Ashmouth x2
Desecration Demon x2
Jarad, Golgari Lich Lord x2

Instants: 7

Altar's Reap x2
Tragic Slip x3
Hunger of the Howlpack x2

Sorceries: 6
Bone Splinters x3
Fungal Sprouting x3

Lands: 24

Forest x12
Swamp x10
Grim Backwoods x2

My Non budget deck will come later, as it still needs a lot of testing. But pretty much add Abrupt Decay and Garruk Relentless (his veil cursed form in particular loves this deck)

This deck pretty much runs on one thing: getting out cheap but useful creatures early on, establish some minimal field presence, then get ready to summon better creatures later on and sacrifice the earlier ones who just come back stronger and thus kicking off my Morbid Spells.

Hunger of the Howlpack is to boost desecration Demon (in particular) to astronomical levels so I can sneak in a surprise Jarad and hit my opponent with a sacrificed 9+/9+ Desecration Demon.

Dawntreader Elk might be an odd choice, but he's saved my life by killing two birds with one stone: he got me my third swamp/forest I needed for my Reaper from the Abyss or my Vorapede and kicked off my Morbid spells. He's very handy in the right situation.

Obvious contenders for MB are Disciple of Bolas and Geraf's Messenger, but this deck still needs a little bit of testing and stabilizing before I change my formula by adding too much Black.