ANIMALS
a blessing of unicorns
a herd of elephants
a crash of rhinos
a pride of lions
a leap of leopards
a mob of kangaroos
a gaggle of geese
a paddling of ducks
a murder of ravens
a mess of officers
an exaltation of larks
a charm of finches
an ostentation of peacocks
a parliament of owls
a hive of bees
a plague of locusts
an army/colony of ants
a pod of whales
a bed of oysters
an army of frogs
a knot of toads
a nest of vipers

OTHER
an armada of ships
a grove of trees
a host of angels
a conflagration of arsonists

See further here.