1979 - Mary is probably uncomfortable and tired of being pregnant.
1990 - Around the time when John investigates some grave-robbing in Windom, Minnesota, and meets a nurse...and "one gets past the goalie."
2004 - Sometime in early 2004, Sam begins dating Jessica Moore.
2006 - This may be shortly after the boys investigated Bloody Mary - which means Sam might be giving his eyes a rest.
2007 - Sam and Dean give up trying to look for Ava, and instead try to figure out why people keep dying at an old Inn in Cornwall, Conneticut
2008 - The boys hunt a coven of witches who have a very unfortunate book-club.
2009 - Dean recovers from his injuries after being beaten by Alistair.
2010 - Possibly around the time that Sam and a teenage warlock switch bodies.
2011 - Dean is living with Lisa and Ben Braeden in Cicero, Indiana; Sam's soulless body is hunting solo (and making amoral decisions); and Sam's soul is being tortured in the cage by Lucifer and Michael.