In his comment on Être et avoir, Anthony mentioned Spellbound, a wonderful documentary on children competing in spelling bees (contests in which competitors are eliminated as they fail to spell a given word correctly) in the USA.
This led me to wonder about this expression. Why spelling bee?
It turns out that a number of expressions are commonly built on this model: apple-bee, husking-bee, quilting-bee, etc. According to the Oxford English Dictionary, it is "in allusion to the social character of the insect : a meeting of neighbours to unite their labours for the benefit of one of their number, e.g. as is done still in some parts, when the farmers unite to get in each other’s harvests in succession; usually preceding by a word defining the purpose of the meeting. Hence, with extended sense: a gathering or meeting for some object; esp. spelling-bee, a party assembled to compete in the spelling of words."