An author friend mentioned Duotrope's Digest to me -- and how they've chosen to close their listings to you unless you subscribe there.
Here's another author's take on why "free" isn't owed to users, which I found refreshing and pragmatic.
If you're seeking an alternative to Duotrope for market research, there's a variety to choose from, courtesy of Author Alden -- including the long-standing Ralan.com, of course.
Market listings: Ralan, SFWA's Pro Market List, Spec Lit Foundation's List; submission trackers: Sonar 3, Writer's Planner, The Writer's Database, LibreOffice; and market response statistics: Black Holes, the Write 1/Sub 1 Forum at Absolute Write, The Rejections and Acceptances Log.
Two are new market listings: Submitomancy and The Submission Grinder. I've linked the Grinder in case you'd like to help them out; for all ten links, please see Author Alden, above.