The Levelator, from GigaVox Media does one thing, does it well and has no bells and whistles to confuse you. In fact, it has no real settings at all. It takes your audio file (WAV and AIFF files at the moment) and normalizes the volume giving you a much more polished and consistent sounding podcast. It basically saves you what can often be hours of manual adjustments.
Levelator requires Java 1.5 so it needs at least Mac OS X 10.4, but it's Universal Binary and free for personal non-commercial use. Runs on Windows too, if you care. It's in very early beta (Version 0.1b). The download page says "...the download and install mechanism is a little sloppy. We'll be making this much nicer over the days and weeks to come, but we didn't want to hold back The Levelator, the core functionality of which is far more solid." In my limited testing this evening it seems to get the job done. I used a 20-second clip of a voicemail message that has 2 of us speaking (one of us actually yelling from across the room) and the original levels are horrible, as you might imagine. A split second after I dropped it onto The Levelator it was done and the difference in the playback audio was impressive. I also found a pointer to How-To use The Levelator with GarageBand's compressed files - which I think I'll be sending to our resident Podcast producer (I'm talking to you, Chartier) here at TUAW HQ.
If you dabble in podcasts yourself, download this puppy and take it for a spin. You might like it!
[via Steve Rubel's del.icio.us links]