I like to listen to books on tape/CD. I used to walk around with my walkman CD player but now that I have an iPhone I like to copy them onto that. Here's an easy way to convert the books to audiobook format after they are copied into iTunes.
Right-click a track, or group of tracks (I do a CD's worth at a time) and select Get Info, head to the Options tab, and then select Audiobook from the Media Kind drop-down menu. The file will instantly leave your Music library and head straight for your Audiobook library. To mark multiple files at once, just select them all and go through the same process. The only remaining step is to tick the Remember Position checkbox if you haven't already, and your tracks should now have easily found their way to your Audiobooks section, and even better, they should work like an audiobook.