Taking the pressure of face-to-face connection, social media is the perfect environment to meet and engage with people online. Certain tools can enable you to search for like-minded people or certain people in roles, industries or stages in their career that offline networking simply can provide with such ease.
Commenting, engaging, connecting and interacting in conversation is a great way to network online - just ensure what you are adding is valuable.
Your goal with social media networking should always be to take the conversation offline.