If you are looking for a Real Estate networking is a few like Trulia, Realtors.com, Zillow, Linkedin, corenetglobal.com, etc. There all allow you to develop relationships with clients and another professionals like you that can add to your practice.
By far, an outstanding website with a strong internet presence is #1. My business doubled last year due to working hard on SEO, and taking every opportunity that came along to dominate my market on the internet--including purchasing 100% of the main search opportunity right here on Trulia. As a result rarely a day goes by without at least one email message from either a Seller or Buyer.