My idea is that the site would be a minimalist layout with 50 servers on a page. They could be sorted by ranking (Players can sign up for an account and upvote/downvote servers, provide reviews etc.), name, gamemode type etc. The server owners would be able to put a direct link to their content pack and forums, and each server would have a clickable link which launches Garry’s Mod and joins the server.
I’m sure I’d be able to integrate other useful features, but those are my thoughts for the minute.