Some heavy hitters from the worlds of online entertainment and sports are hatching a new Internet venture in Seattle. 

Former Rivals.com Chief Executive Jim Heckman, former Fox Interactive Media boss Ross Levinsohn and former IGN Entertainment vice president Mark Stieglitz are involved in a new startup company called 5to1.com, TechFlash has learned.

It is not known what the Internet executives are building, and in an email this afternoon Heckman wouldn't offer any clues.  The Seattle entrepreneur -- whose past ventures include Rivals.com, Zazzle and Scout.com --  said the company is trying to operate in "stealth" mode. 

Corporate documents filed in Washington state list Heckman as president, and former Fox Interactive Media chief revenue officer Michael Barrett as chairman. The business was incorporated last September in Washington state, with SEC filings showing a corporate address in the University District in Seattle.

According to the SEC filings, 5to1.com has raised $2 million of a $3.2 million equity fundraising.  Those documents also list Levinsohn -- now a partner in the $1.5 billion Velocity Interactive Group -- as a director in 5to1.com.

Levinsohn (pictured) and Heckman have quite a history together. As the head honcho at Fox Interactive Media, Levinsohn led the purchase of Heckman's online sports network, Scout.com, in 2005. That deal -- valued at about $60 million -- came just a few weeks after Fox gobbled up MySpace for $580 million.

The sale of Scout.com was validation for Heckman, who became entangled in a University of Washington football recruiting scandal in the early 90s and took the fall when heavily-funded Rivals.com collapsed at the turn of the last decade. After the sale, Levinsohn convinved Heckman to work full-time at Fox Interactive Media's headquarters in California. 

The people involved in the new venture have multiple layers of connections, most of which are tied to Levinsohn and Heckman.

Dale Strang, a former executive vice president and general manager of IGN Entertainment's media division, is listed as an executive at 5to1.com in the filing. A leading online gaming site, IGN was purchased by Fox Interactive Media for $650 million three years ago.

The company's Web site is registered to Stieglitz, who previously worked with Heckman and Levinsohn at Fox Interactive Media. (Stieglitz also worked at Zazzle) 

On Stieglitz's LinkedIn page, his title is listed as general manager and COO of 5to1.com. Stieglitz describes the company as a "stealth startup" that plans to launch in mid-2009. 

Another former Fox Interactive Media veteran whose working on 5to1.com -- John Smelzer -- describes the startup in his LinkedIn profile as an "unique advertising marketplace."  And former SecondSpace executive Alok Sinha, who is listed as 5to1.com's CTO, also indicates that the startup is attacking the online advertising space.

Stay tuned as more details emerge about what could be very intriguing new startup.