Paul Nicholson has published a list of VLF (and some LF/MF) milestones:
http://abelian.org/vlf/amateur-radio/
It’s interesting to see the pace of advancements in this field. In 2010 receiving a carrier (with lots of power and a huge antenna) 900km away was a big achievement. In 2017 sending a short message using a much smaller antenna is normal.