Zombidays - Here's an anthology for all you zombie lovers. This one gives you plenty of words to play with (5-8k) but your story must be holiday themed. There is a list of holidays given for you to choose from. No deadline for submissions yet but don't wait too long.
Whortleberry Press has two anthologies taking submissions now. One for Halloween and one for Christmas. Be sure to check out their guidelines and deadlines. These also have themes so be aware of that.
Short Story America - all genres and from 500 to 12k - I think this market might be very literary.
Port Iris - open to most genres and up to 5k. You'll have to scroll down a bit on the page to find the guidelines. Or at least I did...
Kasma - mostly science fiction but doesn't limit themselves. If they like it, they'll publish it.
Now, go submit something!