Feature Request: Concurrent Trade Limit

How difficult would it be to implement a user-configurable "trade limit"? I get inundated pretty often with 10+ trade requests and it is hard to stay on top of them, even if the trade ends up getting canceled. I'd like, may as a premium feature, the ability to put a cap on concurrent trades. Being able to limit how many proposals I get would be great and would ensure that I can give every proposal a good amount of attention. I figure that trades would count towards this limit until at least one of the parties has marked their cards as shipped.