I got the idea on how Evernote 2.x uses filters to autotag records. Since some time we have tags in PersonalBrain but we have to manually tag the thoughts.
I would like to add a filter-rule to a tag and that personalbrain will then execute it and add a tag to the resulting thoughts or mayby make the resulting thoughts childs of a certain thought.
This would make it easy to add usefull metadata to your data in PB.
I think a lot of the functionality is already available in the reports section but could be a little expanded.