Okay, so this one isn't too hard, since you could pretty much just run Mononoke as a D&D game, but I was watching Mononoke and taking notes on gods/spirits/demons anyway, so I figured I'd go ahead and slap this bad boy together. Enjoy!
D100 D&Dables from Princess Mononoke
1 Giant beasts guarding a magical forest2 Writhey wormy oily corruption infesting a beast
3 A demon that makes everything around it wither and die
4 A demon cloaked in a halo of shadow
5 Something vile possessing a naturespirit
6 A custom to address unknown spirit beings with respect, even if evil
7 A demon that targets the weak/defenseless
8 A corrupting touch that spreads and causes death
9 Bleeding out the corrupting sludge, it dissolves and dissipates
10 A curse that makes you stronger and more deadly, but slowly kills you
11 A mark of a demon with a mind of its own that yearns for violence
12 A curse that makes powerful negative emotions visible as snakey ghost things
13 A Nameless god of rage and hate
14 A monster that will rot incredibly quickly if killed
15 A powerful beast hurls a Death curse
16 Iron is a bane to spirit creatures
17 A small shrine at a beautiful miniature waterfall
18 A land filled with Angry ghosts
19 Warriors massacring a village
20 Giant beasts
21 The Deer God
22 The Spirit of the Forest
23 A girl rasied by wolves
24 A warrior with a minimalist clay mask and animal furs
25 A Giant Wolf God with two tails
26 Tiny funny little tree spirits with rattling heads
27 Minor spirits that demand respect or will lead you astray
28 A tree that is the mother of dozens of spirits
29 Footprints that attract bugs and other small living things
30 A huge deer with a humanish face and tons of antlers
31 A Giant Angry boar attacking warriors armed with flaming arrows
32 A Stampede of giant angry boars
33 The blood of the deer god can heal any wound
34 Glowing eyed ape spirits that want to eat people to take their strength
35 Tiny spirits that look like bugs all over the place
36 A sacred island where it is said you can leave someone with an offering to be healed by a god
37 Ghostly extinct animals flying around
38 Thousands of little spirits greet a returning god
39 A god that takes different from by night and day
40 A huge, giant gelatinous humanoid figure with swirly designs all over its body trailing a mane of goopy stuff
41 Life springing up and dying remarkably quickly in the footsteps of a god
42 An aged, blind, and decrepit boar god
43 A Nature god of both life and death
44 A wounded god afraid to die, being corrupted into a demon
45 A curse that tears your soul apart before killing you
46 Spirits that grow small and stupid over time
47 Boars covered in swirly patterns of mud warpaint
48 A delusional, dying god followed by his enemies
49 A god coughing up blood and being overcome by goopy corruption and going mad
50 A goopy demon is bigger on the inside than the outside
51 A god killed by a new weapon
52 A dead god leaking goopy godstuff that turns into a black ooze seeping the life from all it touches
53 All of the spirits in a forest have fallen dead
54 A headless, amorphous god that can’t hold its form seeking its head
55 The head of a god in an iron box
56 A ruler offers a massive reward for the head of a god
57 Tides of life-sucking godstuff flowing over the mountains
58 A deadly plague pursues a group running with the head of a god
59 A disaster that can only be averted by returning the head of a god
60 A town destroyed by a fallen god
61 A reborn forest in the blood of a dead god
62 Riding Elk
63 An exotically dressed outsider from a culture thought extinct
64 A preternaturally skilled archer
65 A Primitive Flame Thrower
66 A warrior in face paint and primitive jewelry, face covered in blood
67 An industrial fortress on a steep island surrounded by palisades and stakes
68 A primitive, human-powered industrial works
69 Extremely skilled Leper craftsmen
70 A primitive warrior on an assassination mission
71 A huge forge that must not be allowed to go out for a town's livelihood
72 Umbrellas to catch arrows
73 A charge stopped by a small group armed with guns
74 Warrior monks with guns
75 A town run by a formidable woman who will do anything for the outcast and powerless in society
76 An unscrupulous monk who is scheming to get a massive reward from an emperor
77 Burning noxious smoke to confound the sense of smell of beasts
78 Rock grenades to defend a high place
79 Buried land mines on a battlefield
80 A town defended by women and lepers with superior weapons
81 A huge forge burning down
82 The last village of a dying people, deep in the forest
83 An old man in a watchtower has spotted a dire threat
84 A town run by former brothel workers
85 A lord's army besieging an economically important town
86 A shipment of badly needed food attacked by wild beasts
87 A village wise woman who can read fate by casting stones
88 A brave prince, cursed to die and cast out of his village
89 A shrine built on to the side of a mountain
90 A pool where gods gather to heal or die
91 A smart alecky woman and her hapless husband
92 A young couple, one dedicated to civilization, the other to nature
93 A new, compact gun, suitable for women and smaller people
94 Hunters that coat themselves in blood and wear skins to mask their scent
95 A leader, wounded almost to death, makes peace with her enemies
96 A monastary, local lord, and village leader all squabble over a natural resource
97 A village battles the inhabitants of a magic forest to mine the land
98 A duel between a town's leader and a crazed druid
99 A dim-witted, short tempered, but extremely loyal chief of the guard
100 A destroyed town, determined to rebuild
