Altcoins that reward user acquisition?

[petkanics]

Are there any examples of Altcoins that have an elegant design around providing incentives for introducing new users to the network? For example, new addresses/accounts could reference their referrer address, and a portion of block rewards could be allocated to a pool that gets split amongst referrers? I could see this as useful in a network like Steem where there's clear benefit to increasing the user count and participation in the network. Has anyone done a nice job of building this in at the protocol level from the beginning?

Also, first time poster here. Good to be on bitcointalk!

[rapazev]

never saw this.... referral is a pyramid way to scam people so i wouldn't trust in a coin with this.