Because of the current economy, activity on social networking websites has gone through the roof. When I visit the forums and discussions on LinkedIn, I see many recruiters and job candidates actively looking for various types of opportunities. Some are in complete career transition while others are simply looking for a minor change.
Have you been growing your social network? Even if you're in a stable position and you don't see yourself going anywhere anytime soon, I'd encourage you to maintain relationships with old colleagues, classmates, and co-workers. I admit that networking can be tiring and time-consuming, but the intangible benefits are worth that periodic investment.