In the modern-day version of the California Gold Rush, there are many entrepreneurs looking to get rich the way Levi Strauss did; by helping the prospectors. The prospectors in this case are startup founders. It’s a trend that people in San Francisco and Silicon Valley are calling “startups serving startups.”

These companies do a wide variety of things, from payroll and customer support, to catering and financial planning for employees. They are catching peoples’ attention not just because of how fast they are growing, but because they have a business model that is symbiotic with the health of other startups. As a result they are specializing their solutions for different parts of small business, creating efficient sub-systems for companies that would never have the resources to spec and build such systems themselves.

“There’s been growth in a lot of these types of companies,” says Arjun Dev Arora, the founder of ReTargeter and an investor who advises entrepreneurs.

These founders have discovered a market for their products. They are plugging into startups because that’s where they can find influencers who might spread the word about their products. Working with startups has become kind of a marketing channel to some degree because many of those people are early adopters.”

Advisor is a business that provides back office services for more than 115 startups. It does accounting, bookkeeping, HR, sales and marketing strategy, and even board meeting preparation.

Advisor founder Mike Jacobson says the company was born out of a desire to help startups that were “getting the shaft” from service providers who weren’t working in their best interest. “Startups have to focus time and money on building and launching their product as well as customer acquisition,” he said. “Last thing they need is people using their money unwisely.”

What seems to be taking form is a kind of mutually supported ecosystem of these companies embedded in the larger Bay Area’s startup culture. Tushar Kumar, wealth management adviser at Northwestern Mutual, works primarily with startup founders and tech workers in the area. He says connecting founders to other founders and even investors is something his team does, even though it goes beyond what a traditional financial planning service usually does.

We try to connect venture capitalists with entrepreneurs who need funding. We provide that access to VCs. It makes us more than your traditional money management firm. Most advisers will be ready and willing to manage your wealth, but we fight tooth and nail for a client to build that wealth in the first place and we try to make ourselves central to that process.

Kumar meets multiple days a week with individual employees at Twitter and other startups. Many of them have just come into a significant amount of money, or have experienced a “liquidity event,” as he calls it. These are folks who were making $70,000 or $80,000 a year and are now suddenly worth half a million dollars. As he helps these tech employees manage their newfound money, they refer him to their friends who need the same thing.