As a network business, you need specific hacks to get to scale. This usually means piggybacking on other platforms. Whatever hack you choose, you need to do it well and aggressively.
LinkedIn and Facebook hacked the e-mail platform: They asked users to upload their address book and then sent e-mails to their contacts.
DoSomething hacked memes: they took funny pictures aligned with their mission, turned them into memes and released them into social media with a message at the end "... and here's what we're doing at DoSomething". It worked because the memes were shared a lot.