The preliminary Nebula ballot just came out. There's a bunch of worthy stuff on there, although due to its incomprehensible eligibility system much of it may seem old enough to have been honored in previous years. (Do not try to understand; it's a flawed, overcomplicated system.) Anyway, The Magazine of Fantasy and Science Fiction has just put up a whole bunch of stories from the ballot for free online. These include several of my favorite stories from the past few years. I'm going to list them below, and highly recommend checking them out. (And then subscribing!) That said, I'm sure every story F&SF has on the ballot is worth your time.
But I think these are worth more of your time:
"Start the Clock," Benjamin Rosenbaum
"Cold Fires," M. Rickert (Do NOT miss this story!)
"The End of the World as We Know It," Dale Baley (There are a couple of sections of this story that have stuck with me as much as any fiction that acknowledges 9/11.)
"Keyboard Practice, Consisting of an Aria with Diverse Variations for the Harpsichord with Two Manuals," John G. McDaid
"I Live With You," Carol Emshwiller (Seriously, one of the best stories I read last year.)
"Magic for Beginners," Kelly Link (Maybe my very favorite story I read last year and one of my favorites of Kelly's, which is saying something.)
So, what are you waiting for?