Brian Alden: Your professional network is by far the most important resource for your career. But it's not something that will grow very far on its own. Like any relationship, your career connections take effort.
If you are just starting to build a network, start by looking to social media. Utilize tools such as Facebook and LinkedIn to stay in touch with professional contacts and introduce yourself to new ones.
Don't forget to work on those relationships with your current coworkers. Participate in after work functions like happy hours and company events. Use these opportunities to socialize and introduce yourself to people you would not have had a chance to meet otherwise.
Continue to social interactions outside of your current sphere. Join a professional association in your area and attend chapter meetings. Don't be shy in asking for introduction. Use your current connections to make more connections. That's the only way to grow your network.
Just keep in mind that not everyone would be a good addition to your network. You will need to jump in and get your hands dirty to find those great connections that will come in handy in the future. The more people you meet and cultivate relationships with, the better chance you will have at landing a job should you ever find yourself on the hunt.
The old adage is not what you know, it's who you know, couldn't be more true in the workforce. Just remember that an introduction is not enough, you need to keep in touch with your connections and build those relationships.