This would be awesome but would require lots of efforts, it would be neat to have some kind of AJAX database search function.
The quick and simple solution would be to just ad a Sub-Forum below each type of marketplace like this example:
Domains For Sale - Fixed Price
Sub Forum - LLLL.com
Domains For Sale - Make Offer
Sub Forum - LLLL.com
Domains For Sale - Auctions
Sub Forum - LLLL.com
High Priced Domains
Sub Forum - LLLL.com
The question is if we should include the most common ones or just call it "Acronyms".
As you pointed out the seller wants the greatest exposure of his domains, buyer wants to see what he is looking for. I believe that Sub-Forums is the best solution for this.
I have as most of us both ordinary domains and some LLLL.com's. When i want to sell my ordinary names (Non LLLL) I want the maximum exposure since i never know beforehand who might be interested in my names. But since the LLLL.com explosion this is no longer the case.
The LLLL domains have taken over the marketplace, it is totally swamped with LLLL's. The result is that it's becoming harder and harder for both seller and buyer of ordinary domains to find each other. The Marketplace has in fact become a LLLL Marketplace with a minority of ordinary domains. The LLLL segment dominates the marketplace today and there is no end in sight for this segment as demand is increasing by the day.
It's almost getting difficult for buyers of LLLL's to find the LLLL niche they are interested in! The LLLL market is in need of getting more organized IMHO.
Creating a LLLL/Acronyms Sub-Forum would make it easier for LLLL sellers and buyers to do business with each other. It would also increase and optimize the exposure for the LLLL market since it would be obvious for everyone where to look for these domains.
Just my $0.002 Cents