PlayBar is a simple way to stream and queue MP3 files. It was designed for the purpose of listening to hour long podcasts without needed a separate window/dock icon (Quicktime) or having to add the files to any sort of database (iTunes).
You can download and open audio files directly or drag a URL to the icon to have it stream directly. If a podcast is playing, PlayBar will queue the next one up.
Clicking the menubar icon brings up the window, right-clicking brings up the menu, and middle-clicking pauses the episode.
