Anyone who will stand still long enough will have heard me enthuse about this short story, which was my favourite short story I read last year. It was Nebula-nominated, and it's online until Hugo nominations are finished. Even if you aren't eligible to nominate for Hugos, you probably want to read this because it's brilliant.
http://www.sarahpinsker.com/highway1
http://www.sarahpinsker.com/highway1