A few off the top of my head that I haven't seen mentioned so far:
The Cold Equations by Tom Godwin
The Gentle Seduction by Marc Stiegler
The Light of Other Days by Bob Shaw
Magic for Beginners by Kelly Link*
Impossible Dreams by Tim Pratt
Eight Episodes by Robert Reed
The actual short story Magic for Beginners that I mean isn't in the free download for licensing reasons-- you'd have to buy the collection
Magic for Beginners or the collection
Pretty Monsters to get that. Which you should do, along with the collection
Stranger Things Happen.