Another visual how-to for the Content Query Web Part was just posted. While the previous one we blogged about discussed the use of the CommonViewFields property, this one also goes into how to use the QueryOverride and the DataColumnRenames property. With all three, you can do quite a lot with this web part, in terms of what data you fetch, what columns come along with the data, and then what ultimately gets displayed.
I'm happy to hear about ways people have customized this part for their specific scenarios, as well as general questions on what you can/can't do with the Content Query Web Part by customizing its backing properties.
George Perantatos, ECM Program Manager