It doesn't need referred by, but it's harder to get approved.
Just hit my sig and check Parked.com, it brings about same revenue and is fast to join, approve, and move all domains there, almost all domains have well picked AD keywords from domain name.
I have tried dozens of parking options, but my #1 choice is Domain Sponsor. Easy to set up, decent templates, good reporting options, on-time payouts, and reliably high revenues.