Digital archival and preservation of games is challenging, especially when applied to mods that are dependent on the game they're based on. It's only a question of time before sites like moddb, planetphillips, HLC & co go under, or Valve breaks the mod pipeline once again.
I'm no expert on the topic of HL1 mods, but I'd be surprised if someone had already properly preserved hl1 mods for future generations. So I'm sorta proposing that we take the initiative today, before it gets any worse.
What are some mods that should take absolute high-priority? What are some mods that should be disregarded despite their popularity? Should we attempt preserving multiplayer mods? Where do we safely store the files for years to come?