As you know, we spend a lot of our time checking out new applications for the iPhone. And while many of these apps are created by independent developers, some companies are actually raising venture capital in an effort to try to profit off Apple's mobile ecosystem.

It is a risky strategy to build on the back of another's platform, as was pointed out in my story last week by Seattle venture capitalist Bill Bryant.

Nonetheless, venture dollars are flowing into iPhone app startups at a decent clip. A new study by ChubbyBrain indicates that 17 startup companies -- whose iPhone applications are core to what they do -- have raised $102 million.

Interestingly, that's a tiny fraction of the estimated 50,000 apps now avaiable in Apple's app store. And one could argue -- as ChubbyBrain points out -- that $102 million is actually a small number considering what some believe is the game-changing potential of the iPhone.

Still, I am aware of at least three Seattle area startups that have raised venture capital in the iPhone arena.

--Pelago -- maker of Whrrl -- is backed by Kleiner Perkins Caufield & Byers, Bezos Expeditions, Trilogy Equity Partners and others. (ChubbyBrain's analysis notes that Pelago was the second biggest beneficiary of VC dollars in the iPhone app space behind iControl).

--Zero260 -- led by wireless veteran David Bluhm -- is a stealthy project backed by Madrona and said to be working on something in the gaming arena.

--Zumobi, a Microsoft spin out formerly known as ZenZui, raised $12 million from Oak Investment Partners, Hunt Ventures and others. But that money came in well before the Seattle company made a transition into iPhone app develoment, releasing apps for entities such as msnbc.com, REI and The Sporting News. (It does not appear that Zumobi is included in the numbers).

It is also probably worth noting that one of the most successful iPhone applications to emerge from a Seattle company -- Urbanspoon's restaurant locator -- was gobbled up by IAC even though the company never took any venture money

ChubbyBrain actually provides a detailed analysis of the iPhone investment trend, comparing the number of iPhones sold to venture investments.

It also looks at the type of companies that are attracting funding in the iPhone app space, with "social networking" and "gaming and entertainment" attracting almost half of the dollars.