PlayBar is a small app that I've been working on very little, but use every single day. I'm not sure it's worth it to upload to the Mac App Store, so I've open sourced it for everyone to use and contribute to.
Listen to long podcasts from your Mac's menu bar without cluttering your dock/desktop (QuickTime) or creating a large database (iTunes). It doesn't track podcasts; that's another app I'm working on.
It's very simple to use. Either open the MP3 file in PlayBar or drag the url directly to the icon. It will create a queue, so you can chain episodes together. Middle-click on the icon to pause without opening the window.