Back in the days (around 2005) I mostly used Soul Seek and IRC.
Thank the lord that Slsk is still running. There is simply soo much material out there Spotify and the like will never have because they were unofficial live bootlegs, weird studio outtakes and obscure EPs and singles.
Case in point: anybody ever listened to "Towering over the Rest?" It's a 20+ track compilation of Radiohead's B-sides and live cuts from 1993-2000. Never officially released, since the tracks were always available inside of individual singles, EPs and 7"s. Listening to it gave me a completely different perspective on the band's output, which I mostly knew through full albums.
Discoveries like that now have to happen via Spotify playlists, and even then you couldn't reproduce that entire compilation simply because Spotify wouldn't have the license for some of those releases, which came out 25 years ago and on labels that no longer exist.
Eventually the school stopped providing internet to the student housing and we got put on the municipal power company open commercial fiber network and got to choose from an array of commercial ISPs; got massive speed upgrades but it removed the community.
It's still around, but I never hear about anyone using it even though it's more flexible than Napster.
A major feature and downside, depending on who you are, is that you can browse all files a user is sharing. This is great for discovering new things, but also means that copyright holders could sue you for all shared files, not just one at a time like with Bittorrent.
Thinking about it, Kazaa was also more flexible than Napster and maybe a stronger household name than DC++.
http://dcplusplus.sourceforge.net/