: an erratic, unpredictable, or extravagant manifestation, action, or notion
The top five instances considered a VAGARY in a search on Google news:
1) The Independent: A criticism of the use of the phrase "the VAGARIES of the ranking system," as pertaining to golf. Author believes there are no VAGARIES to the system; Lee Westwood will succeed Tiger Woods as No. 1 in the world, as of November 1st. If I knew/cared anything about golf I would follow up on this claim. I'm just the messenger.
2) Summit Daily News: New planning commissioner of Breckenridge Town Council says the fate of Breckenridge is "not up to the whim and VAGARY of each commission member, just based on what they like and dislike." Sounds like a fair system is in place. Breckenridge is in Colorado, by the way. Population: 2,665 [July, 2007]
3) New York Times: A post-Katrina follow-up with a high school football team that waited five years for a new home, citing the resilience of the Cajuns (Creole, LA) in maintaining a lifestyle "dependent on the bounty and VAGARY of nature."
4) The Brandeis Hoot: A reference to a "Constitutional VAGARY" that fails to mandate when/how a student group's annual budget must be spent. (I'm not totally sold on the word's usage in this example.)
5) The Detroit News: Questions whether rapper-cum-R&B crooner "Drake" will be able to "cope with every VAGARY of nascent rap stardom?"
According to the news, the world's most pressing VAGARIES are the golf ranking system (or not), the whims of town commission members, hurricanes, a hole in a Union Constitution (a reach), and rap stardom.
My "best usage" vote goes with Number 3. Hurricanes have without a doubt proven themselves to be erratic and unpredictable.