I believe ebook and audiobook are a couple of the search terms you can use to help find audiobooks using LimeWire or other. I believe some also can be found by searching their specific extensions. eg: .m4b, odm, but also the other formats like mp3, m4a, aac, mp4, etc.

How are you intending to play the audiobooks?

As far as the forums go ... an audiobook section? Interesting idea. Will be considered.