Since it comes up nearly every month:
A Dignity of Dragons
A Blot of Hippogriffs
A Grapple of Griffons
A Riddle of Sphinx
A Resurrection of Pheonix
A Continent of Kraken
A Cresting of Sea Horses
A Splash of Mermaids
A Grace of Unicorns
A Thundering of Rocs
A Vengeance of Harpies
A Glare of Cockatrice
A Roaring of Manticores
A Confusion of Chimeras
A Howling of Werewolves