Collective nouns for fantasy critters...

Can anyone point me to a list of collective nouns for make-believe (but common) fantasy critters?  Like... it's a gaggle of geese or a murder of crows.  I need the equivalent for mythological creatures.  Because I'm a geek.

I've been led to believe that some of these have been defined in English heraldry, but I can't find such a compendium.