I'm still accepting submissions through the end of the month (original estimate doubled!) for Mouldwarp Press #1 "Project Mayhem," which is a flash fiction anthology of stories from any genre at 250 words or less each. I will be finalizing at the end of the month regardless, so if you've procrastinated, please keep in mind that 250 words is incredibly easy to write, and I've chosen that length to ensure that you don't have to overthink it.
Send submissions to firstname.lastname@example.org in the body of your email.
The anthology will be published via CreateSpace and Kindle Direct, so it will have formats I like and am ambivalent about. You won't get paid, but you will have a credit, which seems to impress people.
You might also consider 10 Days of Madness: Flash Fiction Frenzy.