Good Audio Books??

[MacBandit]

I'm looking for a few good audio books to try out. I find I rarely have time to actually sit and read a book anymore. I tend to prefer things that are interactive such as the computer. I do a lot of reading online though. I mean a lot. Though recently I've been looking for a way to get into some books again and audio books seem like a good way since I can't stand the radio but have to have something playing while in the car.

My preferences are Scif-Fi, Fantasy, Fiction, Geology/Earth Sciences, Astronomy, and educational books on new technologies.

Anyone have any suggestions?