It would be nice to have a board, kinda like a reverse AH, for buyers to post offers in crowns or energy to, with an exact item name and a quantity of an item. Maybe even with up to 3 UVs from 9 dropdowns (like [damage bonus vs gremlins][medium][or higher]). The crowns or energy will be charged when posting (like an item in AH) and refunded via mail, if the buyer cancels the offer or it times out.

Sellers can see a list of all offers and search/sort it. To trade their item, they can turn it in (with an input box like in some missions or AH) and submit it. The seler can not turn in an item that doesnt match the name or the UVs exactly as specified. (Therefore a spelling error makes the trade impossible; but I think we shouldnt have a complete list of all items in the game. That woulld be some weird kind of spoiler thing.) The seller will then receive the crowns/energy and the buyer the item; both via mail.

To prevent ppl from flooding the board with offers, there can be a limit per account. So one would cancel an older offer if he already reached the limi, but has a more urgent desire.

This would enable players from different timezones to trade (rare) items.

It could also help to trade anonymously (if the design doesnt say who posted or agreed to an offer), so even players who dont ge along or put each other on ignore could trade, even though they normally would not be able to communicate and agree on a deal with each other.

Also this would be a secure method to do an asynchronous trade, which is currently done insecruely via mail. At the moment a scammer could pretend to want to trade an item by in game mail outside of the games (maybe via forums or some other form of communication), but then refuse to send his part of the deal. This Trading Board would prevent that, because the game makes sure all parts of the deal are submitted, completing the deal.