With the World Series back in San Francisco (yes!), the depth of support for the Giants by the local fan base amazes everyone who visits this place.

The town is awash in orange and black jackets, hats, T-shirts, and blankets, not to mention Panda hats, baby giraffe hats, and much, much more.

Even the buses proudly display messages reading “Go Giants!”

Social media sites like Facebook and Twitter are alive with fans posting and sharing photos, links, and exhortations in support of their stars.

Amidst all this frenzy is a local startup, the Virtual Fan Network (VFN) that has radically updated that old tradition of the collectible baseball card that was once a part of so many kids’ childhoods.

The result is a free digital fan card, interactive and with real-time updates, including the relevant social media chatter, the latest stats, photos and video.

VFN has cards for over 1,200 athletes, but who was the very first one to sign up when the company launched last year?

Giants’ pitcher Tim Lincecum.

“Tim has a lot of very forward-looking people on his team,” says VFN founder Brian Wilhite, himself a former shortstop in college at LSU.

In this case, the “team” he is referring to includes Lincecum’s agents and business partners, which include a T-shirt company.

The enigmatic pitcher also has an active presence on social media. As of earlier today, Lincecum had over 458,000 “likes” on Facebook, for example.

Three other Giants have since joined Lincecum on VFN – fellow pitchers Matt Cain and Barry Zito, and slugging outfielder Hunter Pence.

Of the four, Pence is by far the most active on social media. “Hunter is crazy active on Facebook and Twitter,” says Wilhite. “He takes it to a whole new level.”

This kind of interaction and engagement with fans, which was never possible before digital media, represents an opportunity for athletes to take more control of their own brands and earn new revenue streams.

Which is exactly what VFN is about.

“We're unlocking the digital advertising media spend for athletes,” says Wilhite. “They’ve never had access to that before.”

At the very top of each VFN card is what looks a bit like a banner ad. This is where companies like Verizon, All State, Gatorade, The Sporting News, and others are running advertising campaigns targeted at fans.

A typical media buy of this type may yield around $10,000 for the athlete, although Wilhite says several of VFN’s sports stars are approaching “six-figures” at this point.

Wilhite stresses that VFN is not just for “A List” athletes, but for all athletes. In that regard, he points to a partnership with the Major League Baseball Players Association to promote all of those active in the sport today.

“We work with guys who are not superstars but maybe utility players, like Mike Fontenot or Ryan Theriot,” he says. “They all have fan bases somewhere, like where they played in high school or college, and we can target those local areas with advertising campaigns quite easily.”

VFN has recorded 50 million ad impressions so far and is growing fast. One surprise is how popular many American athletes are overseas.

“We’ve discovered that the fan base of the athletes, especially baseball players,  knows no boundaries -- it is global,” says Wilhite. “Lincecum is very popular in Southeast Asia.”

(I suspect that may be partly because Lincecum is part Filipino; his mother is the daughter of Filipino immigrants.)

Wilhite says the large U.S. military deployments overseas are probably also driving some of the global demand.

While the cards are available on the web, Wilhite says the company is “mobile first” and that hand-held devices are driving the business. The cards are written in html5, but custom mobile apps are on the way.

The company, which is bootstrapped with one strategic investor, is headquartered downtown and has 12 employees, including a former senior engineer from Google.

VFN anticipates earning over $1 million revenues this year and projects reaching $7 million in 2013. Ecommerce is being integrated into the content. (Some athletes, like Lincecum, already have “shop” as an option on their cards.)

Since many of the athletes are active with charities, links to those activities are on the cards also, so basically fans can find everything they want to know about the stars in one place.

Beyond that, Wilhite envisions a company that will just keep growing.

“Every year there are new sports heroes born. And their fan bases don't abandon them after they've stopped playing.”

Former NFL quarterback Brett Favre is a spokesperson for the company, for example.

And although the younger set (15-35) of fans are very active on VFN, as you would expect, older demographics, such as executives who are fans of pro golfers, also form a significant base, one that is also easily targeted in this digital age of online advertising.