365 Tomorrows is a website that provides one short speculative fiction story a day for a whole year. While obviously the stories cannot match the narrative quality of a novella or a full-length novel, it does have however the ability to feature a new science fiction concept after another daily.
The site began posting on August 1st 2005, so you have a lot of stories to read through in the archives and more coming each day until July 31st 2006.