They're known as the "Aussie mafia" making some big waves in Silicon Valley - and now the serial entrepreneurs want to bring more of their countrymen along for the ride.

Australians have taken the US tech hub by storm and while many of their big payouts have been kept secret, between them they have hauled in hundreds of millions of dollars through investments and acquisitions in just a few years.

Ryan Junee, from Sydney, sold his first startup, Omnisio, to Google for a rumoured $US15 million ($14.6 million) less than a year after it was created and he's just closed a $US1.25 million funding round for his new company, Inporia.

Junee says basing himself in the Valley has provided invaluable fund raising and networking opportunities. "Silicon Valley is just another world in terms of you go down to a coffee shop and everyone will be there on their laptops coding a startup or pitching a VC or talking about startup companies," he said.

Bardia Housman founded Australia's first free email service, Start.com.au, in 1997 and it quickly became Australia's most trafficked website. It was sold to Looksmart in 1999, when Housman was 25.

Housman, who has been living in the Valley for about four years, founded enterprise software company Business Catalyst and sold it to behemoth Adobe in 2009.

He said combined his two companies were sold for just shy of $100 million.

Now finished with Adobe, Housman has bought a huge 36,000 square foot building in the heart of San Francisco that he wants to transform into an incubator for Australian startups.

"The plan is to eventually have it as a landing pad for Aussie entrepreneurs coming over as a place to get started and meet others. We're still some months off launching," he said.

"The Australian entrepreneur contingent is quite strong here in the Valley, and the help I received initially – and the help I give these days to other entrepreneurs – is priceless when it comes to getting started."

Ben Keighran moved from Sydney to San Francisco in 2007 where he raised $US6.5 million for his mobile social networking company, Bluepulse.

Keighran, who taught himself to code C++ by the time he was 13 and launched a popular bulletin board system that overwhelmed his parents' phone line, was named one of America's Top Entrepreneurs under 25 by BusinessWeek in 2007.

Now Keighran is the CEO and co-founder of Chomp, the leading app search engine. Chomp is backed by some of the biggest venture capital firms in the Valley and counts Ashton Kutcher and Digg founder Kevin Rose as advisors.

"Yesterday we launched a huge search deal with Verizon where Chomp will be the default search engine on all Android phones from Verizon in the country," he said.

Mick Johnson, who cut his teeth in the Sydney tech scene and developed apps including fuel price bargan hunter GasBag, moved to Silicon Valley to start Whereoscope, a company that makes apps that allow parents to track their kids.

Johnson's company was acquired by social networking games behemoth Zynga earlier this year and he now works for Facebook as a mobile product manager.

Another Sydney tech scene heavy hitter who has joined Facebook in the US recently is Lars Rasmussen, who is credited with being one of the inventors of Google Maps. Rasmussen has told friends that Facebook today reminds him of where Google was when he first joined in 2003.

Andrew Lacy, another Australian making waves in the Valley, sold his game app start-up Tapulous in July last year to Disney for millions. He stayed with Disney for a while but has since left the company and it's not clear what his next move is.

The Aussie mafia in Silicon Valley is rounded out by David Jones, who created companies including fraud protection startup ThreatMetrix and Dealsta, and Paul Glendenning, who started engineering consultancy Solidra.

Austrade on hand to help startups

Tony George, who works for Austrade in Los Angeles helping Australian startups get a foothold in the US, said more than 80 Australian companies attended the SXSW Interactive conference in the US this year.

Austrade provides grants and is on hand to help entrepreneurs with research, advice about market entry, referrals to service providers like lawyers and accountants, and most importantly hooking them up directly with potential customers.

George said the Australian tech startup scene was growing, with incubators such as Pollenizer and Startmate, but the conventional wisdom was that startups need to go to the US to raise funds and be exposed to the movers and shakers in the tech industry.

"We encourage companies that want to be in the market to setup an office here. We help them do that," said George.

"Ultimately we want successful Australian businesses selling their services in the US market, so that dollars pour back into the Australian economy."

Junee's meteoric rise

Junee, 31, spent several years working in Sydney for Freelancer.com CEO Matt Barrie's first high-tech success, Sensory Networks, which produced chips for networking equipment.

In 2003, Junee moved to Silicon Valley to study a masters in electrical engineering at Stanford, and continued working for Sensory until 2007 when he and two other Australians, Simon Ratner and Julian Frumar, founded the online video startup Omnisio.

Omnisio officially launched in 2008 with funding from startup incubator Y Combinator, and within months they were demonstrating their technology to the founders of YouTube, Steve Chen and Chad Hurley.

YouTube had been acquired by Google by that stage and in July of 2008 so had Omnisio – for a rumoured $US15 million. Several YouTube features like the ability to annotate videos were born out of Omnisio's technology.

"YouTube was already developing a lot of similar products internally and they saw what we had built in five months with three people versus what their whole team of around 10 engineers had built over a much longer period of time and saw that our product was much better," said Junee.

"I was living off savings and then subsequently credit card debt and it was definitely a matter of either I needed to sell the company or do something to raise income because I probably had another couple of months of credit card limit left before I had to do something drastic."

The trio joined the YouTube team but after a year Junee had already had enough and at the end of 2009 he left to start a new company. He spent 2010 brainstorming ideas but by the end of the year had begun work on his new startup, Inporia, an online shopping recommendation engine.

In May Inporia raised $US1.25 million from a range of investors and Ratner has since left Google to come back to work with Junee. Frumar is working for Google in Paris.

"Inporia is kind of like an online personal shopper in the sense that what we do is we go and crawl all these online fashion stores every few hours recording what they're selling and how much they're selling for and that allows us to detect when things change," he said.

"When an item drops in price or a new item is added to the store, we'll track that."

The technology, still in private beta phase, builds up a taste profile of each user and is then able to recommend clothes that they may like. There are various business models including commissions from sales driven through Inporia and charging retailers for the ability to make targeted offers to users.

"We want to learn as much as we can about you so we can search through the thousands of items and give you 10 that we think you might be interested in," he said.

Junee said eventually he wanted to start bringing the entire buying/checkout process into the Inporia site and could even "skip the retailer altogether and go directly to the brands to sell the product".

He compares Inporia to Pandora, a music service which has classified virtually all songs in existence according to various attributes and recommends tracks to users based on what it has learned about them over time.

"It starts to figure out your music genome, the DNA of your music tastes – we're trying to be the Pandora for fashion," said Junee.

Junee, who now flies planes as a hobby, has come a long way from just a few years ago when he was living off credit card debt and agonising over how to pay for his Stanford tuition. He plans to sell Inporia eventually and then start a new company.

"I'm living in quite a nice apartment here in San Francisco, it's up on the 43rd floor of a building with an awesome view of the city – that's a bit different to how it was back when I was a Standford student," he said.

Aussie mafia derived from PayPal mafia

Junee is not sure where the term Aussie mafia originated but says he believes it is based on the PayPal mafia – the term used to describe the original founders of PayPal who have since gone on to launch a number of huge tech businesses and hedge funds.

Junee has made trips down to Sydney to meet with local entrepreneurs and via the recent Startmate event he helped bring five Australian companies to Silicon Valley. He said two or three had already raised money from angel investors after he taught them to ditch the conservative pitches focused on short-term cash flow and instead woo investors with vision.

"I think it's still a lot easier to start a company out here and raise money," said Junee.

"I've made a huge network of investors and entrepreneurs and friends out here so when it came time for us to raise money for this new thing, it was quite easy for us to raise $1.25 million."