SHORT STORY ANTHOLOGIES

Short Story Collections - A collection of short stories complete with age ratings,
 general ratings, and length.

Classic Shorts  - This is a collection of short stories by classic authors. 
The collection is smaller than the above link, but it includes the "cream of the crop".

American Literature - This is a very large collection of American authors, some of which weren’t featured on the previous two websites (like Lovecraft). 

Write a Short Story  - Basics techniques on how to write

Creative Writing Now - Excellent resource for tips and advice, but most valuable for the creative writing prompts.