In its ongoing bid to prove there is a robust and sustainable advertising business in the social-networking space, widget-maker Slide opened a New York City office and hired a big-deal online ad exec.

Of course, because it has to be hip, the office is in the always trendy West Village, instead of uptown in Manhattan on Madison Avenue.

The new director of ad sales is Jason Bitensky, who comes to Slide from his post as director of national sales at AOL (TWX) Media Networks/Platform-A. Previous to that, he worked at Comcast (CMCSA).

Until this hire, Slide had only four salespeople, all located at its San Francisco HQ, who sold campaigns and sponsorships for its third-party apps that are hugely popular on sites like Facebook and MySpace (NWS).

Advertisers are most definitely intrigued, experimenting all over the place and interested in different ways of engaging with consumers.

Nonetheless, they are still using tiny “innovation” budgets to test the space and have still not unlocked the treasure chests of big bucks that go to television.

In fact, here is an interesting story on the ad issues apps-makers face in The Wall Street Journal tomorrow.

The not-so-much-money quote: “The push by application companies means more players are competing over what is a relatively small pie. In 2007, U.S. marketers spent $600 million advertising on social media, a sliver of the $18 billion spent on interactive advertising that year, according to Forrester Research. The number is forecast to spike to $6.9 billion by 2012.”

Still, said Max Levchin, CEO of Slide, about the move in a statement: “The success of campaigns on our popular products, such as SuperPoke!, Top Friends and FunWall, has attracted the attention of not only top brands, but also top talent like Jason.”

BoomTown shall agree to disagree with our favorite widget king about SuperPoke’s potential as an ad vehicle.

But it is entirely true that Slide and other apps-makers have to convince big brands that the social-networking phenomenon is here to stay and is effective, well beyond its viral popularity and huge valuations given to companies in the space.

Earlier this year, Slide–founded in 2005–got a $50 million round of funding that valued the company at $550 million.

And here’s a disturbing, but very funny, spoof video about where all this SuperPoking eventually ends up: