My favorite Nullsoft software that came out the end of this era was WASTE [1].

Peer-to-peer (back when P2P was all the rage), encrypted, decentralized private networks.

Group of friends and I used it post-college as a way to share files and chat, and was much better than AIM or other instant messaging at the time.

1. https://en.wikipedia.org/wiki/WASTE

I always thought WASTE was so cool, but my family was pretty late get off of dialup to be able to actually use it. Sounds like it's still around in some form, do people actually use it nowadays?