One idea that has been thrown around is to have the "option" to have a new classified listing start it's own thread in the forum, then have the comments attached to that. It brings attention to the ad, and allows discussion about the listing, if needed.
It's not a bad idea, I'm sure it has upsides and downsides.
I'm not real sure if I have a solid grasp on the "Best Offer" feature of the present version, but I did get a lot of complaints about it not working the way people expected it to. I think they mentioned that the listing should have a set price, then a "Make an Offer" type of button where they can privately submit a "Best Offer" to the seller. Then the seller accepts or declines.
The ability for the administrator to set static category thumbnails, and if nothing is set, it can draw from current listings as it does now.
We could definitely use some tweaked permissions "options" for the admin to set for moderators. I don't want to have 100% of the workload in the classifieds, and there are things that the moderators can't do that I would like to have them do.
I also believe that if the user/guest doesn't have the ability to view the classifieds, they should be met with an error message instead of a page with no content on it.
I'm still wading through comments from members and staff from my beta testing, so I'm sure I'll be back with more suggestions/requests.
I know you can't always do everything that is asked for, but I have been looking for a full featured classifieds system for a few of my sites, and I would really like to stick with this.