On my recent trip to Seattle, I visited the offices of iLike in the Capitol Hill section of that lovely Pacific Northwest city to take a video gander at one of the more interesting start ups to emerge from the social-networking arena.

The music discovery site, unlike a lot of others in its sector, has been plugging away for several years with much less funding–about $16 million from the founding Partovi twin brothers, former AOL (TWX) wunderkind Bob Pittman and a big slug from Ticketmaster (IAC)–but with a lot more impact.

Like its competitors, such as Last.fm, it has forged its popularity by focusing on linking its users with one other and musical artists via what they like to listen to.

Kind of like that old shampoo cliché: She told two friends and she told two friends and so on and so on and so on.

It’s actually quite an infectious app and also Web site, with 30 million registered users, and it’s one of the few that is useful on social-networking sites like Facebook, hi5, Orkut and Bebo.

So useful, in fact, that Facebook has selected the service as one of only two “preferred” partners, a designation Facebook announced today at its second developers conference in San Francisco.

iLike was the brainchild of Ali and Hadi Partovi, longtime Web entrepreneurs who have also worked at big companies like Microsoft (MSFT), and whose interest in music and online delivery was the inspiration for the site.

To make money, iLike has a number of businesses.

First and foremost it is essentially a lead-generator for sites like Amazon (AMZN), iTunes, Ticketmaster, and more recently, the Rhapsody subscription music service, with which it just added a somewhat restricted full-song playback offering.

And iLike has just launched an ad platform for concert promoters.

The brand itself, although focused on music right now, obviously has extension possibilities (iLike movies? iLike TV? iLike tacky theme parks?).

Most observers of iLike assume it will sell to a larger entity eventually, such as Ticketmaster, for whom the site has become a major referrer.

But the Partovis–who have sold start ups before–insist they want to build the iLike brand.

Here’s a video interview with Hadi Partovi in which we talk about all this and more, along with a tour of iLike’s offices:

Today, in yet another episode of the Web 2.0 lottery, Social Gaming Network grabbed $15 million in funding for its widgety gaming apps that are popular on Facebook and other social-networking sites.

The round, led by Greylock Partners, Founders Fund, Columbia Capital and Novak Biddle Venture Partners, will go toward expanding its offerings, which include the popular Warbook, and also its network for other developers to create and publish online games on.

SGN grew out of Webs.com, which used to be known as Freewebs.

While BoomTown often makes fun of viral apps, most of which are faddish and juvenile, the better made gaming apps actually are likely to be a real business over time, as long they remain engaging and fun to play as the classic real-life games are.

After all, who ever gets sick of Candyland?

SGN’s games are not quite that, focusing more on strategy and bang-bang that 12-year-old boys of any age so love, but, CEO Shervin Pishevar promises, with increasingly rich features and better graphics.

The business plan? Advertising, of course, especially sponsorships, as well as the sale of virtual goods and premium offerings.

SGN’s other popular online games include FightClub, StreetRace, Jetman, Text Twirl and Free Gifts. It has 1.1 million daily active users mostly across Facebook, but also on Bebo, hi5, and MySpace.

In the space, its main competitor is Zynga (here is a post and video with its founder, Mark Pincus). Naturally, the two bicker back and forth in the blogosphere about size and quality of games.

But it seems to me that there is room for both, so the fighting seems like a lot of noisy, well, game-playing.

Here’s Pishevar talking about the sector: