On a morning walk to work for a few days ago, when I, as usual, listened to a podcast on my iPhone, I happened to accidentally click on an icon I've never noticed earlier - "2x". Suddenly my podcast started playing at two times the speed (at least what it felt like), but without making it difficult listening. It was actually quite easy to keep up with the podcast-dialogue, and after 15 minutes I had completed half an hour long podcast. It feels a bit like skimming through a book, you may miss the details, but get the big picture. And when they suddenly start talking about something that is very interesting you can always return to the "standard speed".
So if you have an iPhone or iPod Touch with OS 3.0, start a podcast and click the 2x-icon in the upper right corner, and you may be able to start optimizing your time!