When you're one of hundreds or even thousands responding to a Web job posting, a smart resumÃ© showing lots of experience may just not be enough. That's where LinkedIn may prove to be essential. "LinkedIn is all about networking, and networking is the best way to find a job," says Rivka Magen, a Herzliya hi-tech executive who has used the social business Web site since it was launched in 2003 to both look for jobs and look for employees. "We all like to hire or use people we know are dependable or are said to be dependable by people we know. So being referred to a hiring manager by someone he/she knows is extra powerful and gives you a leg up. LinkedIn is a Facebook for business people," says Magen. And a profitable one at that. Last year, Sequoia Capital, Greylock Partners and other venture capital firms purchased a 5 percent stake in the California-based company for $53 million, giving the company a post-money valuation of approximately $1 billion. As of October, LinkedIn had more than 30 million registered users. How does it work? The purpose of the site is to allow registered users to maintain a list of contact details of people - called "connections" - they know and trust in business. "When I was job searching, I started with it by simply inviting everyone I know in business to be a LinkedIn contact - to 'link in' with me - from my most recent job back through all jobs, many times reaching out to people I hadn't spoken with in years," explains Magen. "The beauty of it is that it enables you to do it electronically via e-mail quickly - it would take you much more time to call and track down people, getting their phone numbers. "If they accepted, I would send an e-mail asking if I could have a half hour of their time on the phone to to get their perspective on the market, etc. I would try to set up a bunch of these networking calls all day. Before each call, I would also look at their LinkedIn contacts and write down names of people I'd want them to introduce me to." According to Magen, there's a LinkedIn etiquette that should be observed when following up on a connection in order to pick their brains about prospective jobs. â€¢ Make small talk briefly, touch on people you know, the weather, etc., to set a nice tone â€¢ Briefly describe your background and what you're looking for. Send a resumÃ© beforehand, just "to familiarize them with my background." â€¢ Ask them about what they do. Never ask them if they have a job for you. This is a networking call; asking for a job changes the tone. â€¢ And the goal: to ask and get additional names of people they know for you to talk to. "Some people will be more helpful than others, suggesting lots of names and really offering to help. Others are less friendly, and treat the call as an obligation, which is a little short-sighted as they may need help themselves down the road," says Magen. "Some people that I've known for years have been less than helpful and others that don't even know me will often go out of their way. There's all types." Eventually, says Magen, you'll make the magic connection. "Sooner or later certain people will say, 'I know someone who is looking for someone like you - let me send your resumÃ© to them.'" Or: "Call this person - I know they need someone." Laid-off NDS staffer David Goldhar says that he's been on LinkedIn for a few years, but never realized its usefulness until he started his recent job search. "I started networking on LinkedIn and calling people and it's been beneficial. I'm noticing that people who are even still at NDS are using it and getting more connections," he says. Keeping involved with LinkedIn while employed is a smart move, says Ori Shiloh, marketing manager of Nisha, one of the country's top headhunting companies. "It's always good to be networking," he says. Veteran networker Magen offers some other tips on how to make the best use of LinkedIn connections. â€¢ If you see a job posted on-line, you can search Linkedin for names of people at that company. If one of your contacts is connected to them, it will show up. â€¢ If you want to pursue a specific company - maybe you've heard through the grapevine that they might be looking for someone with your skills set, or maybe you just want to "cold call" them - you can search by company and find names of appropriate people to contact. It's possible they may have a connection and be linked to one of your contacts, in which case you'd ask the contact to make an introduction. In today's job search world, it's all about who your friends know.