Here are some markets that you can send stories to. I've also listed other web pages that list a much more comprehensive number of markets than I can (okay, than I am willing) to list here.
Oh yeah. Do I really need to tell you to use your best judgment when selecting a market? I mean, there are some pretty shady people in the world, and the writing business has their fair share.
There. That was my disclaimer. Hope for the best and prepare for the worst, that's what I always say. Okay, so I don't ALWAYS say that, not constantly, like a mantra or anything. Because, you know, then people would think I was stark raving mad. I sometimes say other things too. Then my family tells me to go back into my study.
Anyway, a big thank you to Jack Ewing over at the Short Mystery Fiction Society for a lot of these links.