Contracts listed should not be cross posted as I would imagine a member could only list their contract with one resale company. I can't remember the name of the site but like PP mentioned there was a
DVC search site which pulled listings to list in one location/site, but i don't know how up to date it is. i would see listings on that site but then when i would go to the actual resale site I couldn't find it.
There are 2 resalers that i know have apps.
You can also sign up on all the resale company sites to receive emails with new listings. Usually sent daily.