DaviddesJ
Deity
I wanted a single list of everything that affects happiness. I couldn't find one, so I compiled it myself. If I have some details wrong, please post corrections and I will edit.
HAPPINESS
+X difficulty level
+1 each dye, fur, gems, gold, incense, ivory, silk, silver, spices, sugar, whale, wine
+1 Market per fur, ivory, silk, whale
+1 Forge per gems, gold, silver
+1 Theatre with dye
+1 each Cathedral with incense
+1 hit movies, hit musicals, hit singles
+1 Broadcast Tower (or Eiffel Tower) per hit movies, hit musicals, hit singles
+1 per future tech
+1 each 10% culture
+1 Colosseum per 20% culture
+1 Theatre per 10% culture
+1 Broadcast Tower (or Eiffel Tower) per 10% culture
+1 state religion in city
+1 Palace
+1 each Temple
+2 Cathedral of state religion
+1 Free Religion per religion in city
+1 Colosseum
+1 Notre Dame on continent
+1 Environmentalism per jungle, forest
+1 Hereditary Rule per military unit in city
+2 Nationhood with Barracks
+3 Representation in X largest cities (X=4 to 6, depending on map size)
UNHAPPINESS
+1 each citizen
+1 per 3 citizens, if undefended
+??? war weariness (reduce: 25% Jail, 25% Mt Rushmore, 50% Police State)
+??? cultural inferiority
+1 per slavery used (within last 10 turns, scaled by game speed, or longer if repeated)
+3 per draft used (within last 10 turns, scaled by game speed, or longer if repeated)
+1? each other civ with Emancipation
(Globe Theatre negates all unhappiness)
HAPPINESS
+X difficulty level
+1 each dye, fur, gems, gold, incense, ivory, silk, silver, spices, sugar, whale, wine
+1 Market per fur, ivory, silk, whale
+1 Forge per gems, gold, silver
+1 Theatre with dye
+1 each Cathedral with incense
+1 hit movies, hit musicals, hit singles
+1 Broadcast Tower (or Eiffel Tower) per hit movies, hit musicals, hit singles
+1 per future tech
+1 each 10% culture
+1 Colosseum per 20% culture
+1 Theatre per 10% culture
+1 Broadcast Tower (or Eiffel Tower) per 10% culture
+1 state religion in city
+1 Palace
+1 each Temple
+2 Cathedral of state religion
+1 Free Religion per religion in city
+1 Colosseum
+1 Notre Dame on continent
+1 Environmentalism per jungle, forest
+1 Hereditary Rule per military unit in city
+2 Nationhood with Barracks
+3 Representation in X largest cities (X=4 to 6, depending on map size)
UNHAPPINESS
+1 each citizen
+1 per 3 citizens, if undefended
+??? war weariness (reduce: 25% Jail, 25% Mt Rushmore, 50% Police State)
+??? cultural inferiority
+1 per slavery used (within last 10 turns, scaled by game speed, or longer if repeated)
+3 per draft used (within last 10 turns, scaled by game speed, or longer if repeated)
+1? each other civ with Emancipation
(Globe Theatre negates all unhappiness)