Aeron will raise the AC by 3.
Agares will allow Ashen Veil civs to start a golden age.
Amathon offers good civs the ability to buy a great prophet, or gain some beakers towards their research goal.
Arawn has no effect I believe.
Bhall will warm some squares up temporarily (snow to tundra, tundra to grass, grass to plains, plains to desert.)
Camulos will give a -1 diplomacy modifier with other players.
Ceridwen offers evil civs the ability to buy a great prophet, or gain some beakers towards their research goal.
Cernunnos will allow FoL civs to start a golden age.
Dagda will give a +1 diplomacy modifier with other players.
Danalin will allow OO civs to start a golden age.
Esus will allow CoE civs to start a golden age (and raise the crime rate.)
Junil will allow Order civs to start a golden age.
Kilmorph will allow RoK civs to start a golden age.
Lugus will allow Empyrean civs to start a golden age (and lower the crime rate.)
Mammon gives you 40 gold.
Mulcarn will cool some squares temporarily (desert to plains, plains to tundra, grass to tundra, tundra to snow) and allow Illians to start a golden age.
Nantosuelta has no effect I believe.
Oghma gives you some beakers towards your research goal (25% of the cost.)
Sirona will lower the AC by 3.
Sucellus will heal units.
Tali will put out any smoke/fires.