I have a number of audiobooks that are very long (10 or more CDs). I don't like having them all in separate files because when you leave and come back, you're scrolling through hundreds of files to find the one you were on. Instead, I used an audio editor to combine them in to 3-5 hour files. However, if you are scrubbing through the file and accidentally slip (lift your finger, etc), you've now lost your place in such a large file. I have seen in some podcasts that have chapters, allowing you to use |<< and >>| to skip around, and keeping the scrubbing to within the chapter. Can these be applied to audiobooks? If not, can I tell iTunes that my book is a podcast and set them there? I tried that once but couldn't see how to set chapter markers anywhere.
You can do it with Garageband on a Mac, or using a separate utility on Windows.
Mac with Garageband
There's a detailed guide here, but the concise version is:
If you want the files to appear as audiobooks in iTunes, you may need to select them (in iTunes), and change the Media Kind (Get Info/⌘I, Options tab) to Audiobook.
Windows using Chapter and Verse