I am officially smitten with Duotrope. If you don't already know about it, you should.
Duotrope is "a free writers' resource listing over 2800 current Fiction and Poetry publications." It is a massive fiction and poetry market search engine, searchable by genre, pay rates, length and theme of piece, submission method, and media type. Trying to impress your internet-ignorant grandparents with your latest thriller? Search for print markets that publish crime fiction. Got an existing piece on coming out as a lesbian during the Bush administration? Search for GLBT/Women's/Political themed publications. Been writing a lot of short pieces lately and trying to score some extra spending money? Search for high-paying markets that accept flash fiction by email (save on postage!).
They also have some excellent round-up statistics, like markets that send personal responses and the markets with the fastest/slowest response times and the lowest/highest acceptance percentages. They prudently decline to rank the "most prestigious" markets, but they do provide a list of the markets with the most reported response times (not exactly a measure of popularity, but it at least shows you which magazines most people are eager to report information about), and you can draw your own conclusions about those markets with low acceptance rates. (This can all be found through the section marked "Curious?")
If you register, you can save searches, start building a list of your favorite markets -- and those you want to ignore -- and best of all, you get a free submissions tracker. I've been using Excel, but this is really a lovely feature, and it helps provide (anonymous) data to your fellow (desperate, hungry for information) writers.
Go check it out. It's really amazing.
WHAT'S YOUR FAVORITE FICTION OR POETRY MARKET? I've been recently impressed by the fiction at flashquake, Boston Literary Magazine, and Nanoism.
UPDATE: as of 10:58pm Sunday night, one of the literary magazines I found through Duotrope has accepted a short fiction submission from me. Details and links will eventually follow.