Mobilism, Audiobookbay, yandex (the search engine yes.. very easy if you just use key words in your queries). I'm sure private forums are helpful as well.

Edit: I use mobilism quite a bit and audiobook websites that have links for rapidgator or other hosts. Having a debrid service (all, real, etc) is super helpful because I can usually use the premium link service to convert the link so I can download at full speed. Not all hosts are supported but its not often I find a link from a host that isnt supported. If this does happen, I just bite the bullet and go ahead with a slow download.