Hearing about new social networks usually makes us cringe. Surely by now, all relevant communities of people have a place to share ideas, photos and blogs.

But at this years DEMOFall, Seattle’s LiveMocha launches with a interesting twist. The company mainly focuses on teaching you a new language using the do-it-yourself immersion methods of the popular Rosetta Stone software, but it has blended in a social network to enrich the experience.

LiveMocha is not the only start-up hovering around this concept. It has a competitor, Mango, that also offers free courses, 100 lessons each, in over 13 different languages.

But even though Mango offers more languages (LiveMocha’s got six right now) it’s the social network, paired with its VoIP capabilities and chat rooms, that sets it apart. The key is that, unlike so many of the wannabes in the social network game, LiveMocha’s social network is not the central focus of the site but simply a feature.

The bulk of LiveMocha’s site shares much with Mango, offering around 160 hours of content per language, spread across a number of increasingly advanced courses designed to totally immerse you in a new tongue. Each course will take a dedicated student about a trimester to finish, but, thanks to LiveMocha’s social networking features, the learning can extend far beyond the structured content, into online conversations with native speakers.

The social networking is designed to foster a tit-for-tat exchange: if I want to learn French and you speak French and want to learn English, LiveMocha uses a very basic search that makes it easy for us to connect. You can, of course, create a profile, upload your picture, add some contact information and interests, add friends, and so on, but really, the only important part is what language you speak and what language you want to learn.

However, the company has added some small but nice touches. For example, when you add friends, you can see how far along they are in their lessons and compare your performance to theirs, creating social pressure to push yourself forward.

Refreshingly, LiveMocha is not hinging its business model on advertising. Instead, the site intends to add content accessible only by subscription, and may open up a virtual marketplace for language tutors and take a percentage fee of the transactions. Of course, this all assumes that LiveMocha will be able to attract enough users worldwide to fill out the ranks of people willing to help each other learn languages — no mean feat.

In its press materials, LiveMocha notes that no real innovations have occurred in the self-taught language-learning market since the advent of CD-ROMs. Indeed, Rosetta Stone, the market’s dominant player, is still pushing its product on CDs, and charging a bundle for them. Considering that the language-learning market (on and off computers) is an estimated $20 billion, there’s no shortage of demand.

It was only a matter of time before someone would leverage the web ‘s new technologies to take a shot at the old guard.