There are agencies all over the world, not many if any US based. But models signed with Alternative Agencies work with various clients and still pursue their own interest as well.
The H.V. Quenzer They represent US models too.
Adora BatBrat is signed with Nocturnal Agency but she's most famous for her Youtube channel and blog
She has her own website for booking.
She's a fire performer and alt model. She has her own website called I am Truoble, her own makeup line called I am sin.
She's a multi-talented model, contortionist , and all around performer.
These are examples of famous alternative models that are very well known for their talent and art. As well as published in multiple magazines, books, performed on many stages, have various accounts on facebook, deviant art, model mayhem, youtube, etc.
Different models model different things, it depends on their interest, talent, work, experience, etc.
There's a lot more where they came from and I'm sure there are more to come.