With ESPN putting almost all its talent behind their Insider subscription, Ken Rosenthal, previously of The Sporting News and now with FoxSports is the must-read for trade rumors.
He seems to be very agressive in breaking any news/rumors. And that is exactly what I look for at this time of the season.
(I could have titled this post "Non-Subscriber Sites" to use the current euphemisms but decided to keep the apprently offensive "free" for nostalga's sake when the 'net used to be free.)