If you ever do any recording, mixing, or editing of audio, you'll want to check out Audacity, an open-source audio editor available for Windows, Mac, and Linux/Unix. It's one of those programs that gets its beauty not from a complicated list of features, but from its ability to do a job well with an intuitive interface.

Still, Audacity is pretty versatile, having some built in effects like fade-in/fade-out, bass bost, wahwah, echo, and noise removal, and offering support for VST plug-in effects (which can do just about anything you can think of).

Tool of the month, hands down.