The Unsold XML Site Report is a fairly useful tool for all networks within MyAdMarket. As most networks have XML partners this report can help you monetize your XML traffic better.
The report basically will summarize for a specific date, the network and site that provided you the amount of unsold XML traffic. From the network ids and site ids you would be able to identify your partners which have the unsold traffic and try to communicate with them to lower the unsold.
You can find the report here: