Your paper about #PIM (https://karl-voit.at/tagstore/en/papers.shtml) is an awesome resource for interesting software and concepts. Haven't finished reading yet and already have a few things I want to try.
Links I'm going to check out:
http://blog.ulisesmejias.com/2005/04/26/tag-literacy
https://github.com/novoid/Memacs
#memacs also reminded me of my search for an application that let's me browse all information as a timeline ... here: https://softwarerecs.stackexchange.com/questions/30416/application-to-browse-time-stamped-data-of-different-type