Referring Root Domain in processing rule should work the same as Referring Domains Report in SiteCatalyst.
The former returns values as follows:
As you can see, 'co.jp' and 'ne.jp' seem to be Referring "Second Level" domain. Instead, I would like to have the values as follows:
Kevin at webanalyticsland provides a great way to do this with a plugin, but if you don't have a plugin you can resort to a processing rule, which is not as good as Kevin's plugin, but it's better than being stuck with only the out-of-the-box Referring Domain report or the lengthy Referrers report.
***yes, it's also called "Referring Domain' just like the out-of-the-box report, except with this Referring Domain report via processing rule you will see the full Referring Domain. I think the default Referring Domain report in SiteCatalyst should just be named Referring Root Domain.