Here's a great preview of the Rule 5 draft over at the Pirates' SBNation site, Bucs Dugout.
There seem to be a few interesting players available, although the most interesting will probably be picked up before the Jays pick. I think the Jays could be interested in Tyler Cloyd (RHP), T.J. McFarland (LHP), Cesar Cabral (LHP) and possibly others to stash in the bullpen for a year or forever. Personally I'd take a look at Thommy Pham (OF), Gorman Erickson (C) and Ryan Flaherty (2B/3B): they could all be platoon guys.
Who would you want to drop to the Jays?