I've read a post this morning by 
What they did looks pretty cool. Here's how the business model works, and all this wouldn't be possible without Steem-Engine.
You delegate to their account @Steem.Ninja for at least 7 days and hold the delegation until the payout date.
At the payout date, you will receive some INV tokens, proportionally with your delegated SP compared to other delegators, since there are a fixed number of accounts that can be claimed daily.
Once you have your INV tokens, you can trade them for new 'free' accounts, at a ratio of 1:1 for now. Or you can trade them on Steem-Engine, for STEEMP. You may receive less than 1 INV after a payout, which is normal for most small delegators.
How does it help Steem-Ninja?
Its STEEM Power grows, and it will be able to claim more 'free' accounts daily.
How does it help you?
If you don't have enough SP, you won't be able to claim such a 'free' account yourself, because you wouldn't have enough RCs.
For example, I don't have enough RCs to claim a 'free' account. At current RC costs, dolphins at the 5k SP limit would barely be able to afford to claim one such account per day, without doing much of anything else on the blockchain.
How does it help the ecosystem?
It creates a market, so far for the claimed accounts of Steem.Ninja, but this should be first step before all owners of claimed accounts would be able to participate, I believe.
Do you remember one of the benefits promised in SMTs were RC pools? Well, while this is just one application of putting together SP with the purpose of creating a larger RC pool to claim more 'free' accounts, it is yet another functionality that came out before SMTs did.
I wonder if Steem.Ninja Invite is the first step before Scot.Ninja will be released, as announced by 
The ultimate goal of all this is to improve onboarding, which I hope it will.