I'm a huge fan of audiobooks, and I listen to them almost exclusively in the car. I currently commute around 60-70 minutes a day total, and instead of being frustrated by traffic, I often arrive at work or home excited and invigorated by a new idea that I picked up in my classroom on wheels. However, one thing that I do that often surprises people is that I listen to nearly all my audiobooks at double speed or faster. Fortunately (or perhaps as a consequence), I commute alone!
The San Jose public library system has a huge selection of audio books available for download in MP3 and WMA format, as well as a number of books on CD that can be ripped to MP3, and I have recently begun to purchase more books from Audible.com now that I am not completed blocked by their DRM. I use my Android phone as my portable media center, but I was turned on to the idea of high-speed listening by an iPhone user because Apple has variable-speed playback built in. I use an Android app called Astro Player Nova (the paid version, although they have a free version that also does speedups) that allows me to increase (or decrease) the playback speed, while providing pitch correction so the speaker doesn't sound like a chipmunk. Most audiobooks are recorded at a comfortable speaking pace (~150 words per minute), but most people are able to easily process spoken language at at least 2 times that rate. It is a little daunting at first, but I started out at 25% faster, then gradually increased it until I now start most books at double speed and move up or down according to the book. Although in theory I can probably go even faster, I find that the software begins to clip words together. Yes, I know, blaming the software, not the "wetware"... At that rate, I enjoy a new (unabridged) book nearly every week, and I also find that the faster pace keeps me more alert.
Prior to getting a smartphone, I used a rather cumbersome pipeline (tools glued together with perl) that would convert CDs or MP3s into WAV files, then run these through mplayer to do the speedup, resize them into 2 minute chunks for easier indexing (my old CD player would only start at the beginning of the song, not exactly where I was when the engine stopped), and then finally re-encoding them as MP3s before burning them onto CDs for playback in my CD player. Variable speed playback of audiobooks was actually the deciding factor that pushed me over the edge to a smartphone! DRM protection on the audiobooks is still a nuisance for both WMA files and audible.com files, but tunebite helps.