Science fiction is my favorite genre, and I'm always interested in new ways to find good stories. A friend pointed me toward Escape Pod not long ago.
I generally prefer reading over audio for my consumption of the written word, but there are certainly times when having an audio version is preferable. For instance - making a fairly long-distance drive, or getting some work in on the elliptical machine, or washing dishes. The short stories on Escape Pod fill in those bits of otherwise boring time nicely.
Escape Pod is part of the Escape Artists organization, which also has two other short story podcasts: Psuedopod for horror, and PodCastle for fantasy. I haven't checked out either - plenty to keep me in stories with the sci-fi - but it's cool that they're working with multiple genres. Worth checking out if you like any of those genres and have some time to fill!