I love to use them for long drives, chores, and when I played more video games I found them to be an essential companion. I have strong associations between certain games and certain books (a scene in some Ludlum novel and Grand Theft Auto III by a dam spring to mind) and it's still a pleasant way to set the mind in neutral.
That said, I tend to want to actually read a book that I care about to any real extent, but I'm also the type who re-reads a lot. I found the unabridged Wheel of Time to be something special out of all the audiobooks I've enjoyed though.
Sorry for babbling, I'm a bit passionate about this, although I get a bit sad when people don't read and just listen to books; although I think it's better than nothing for sure.