There are many ways to do networking on the web but I happen to think one of the easiest is to participate in blogs you enjoy by frequently posting relevant content. Blog comment posting is very much like standing around chatting with a group of folks at a networking event (except you don’t have to balance the Swedish meatball plate on your wine glass.)
It is not an easy or quick method, but over time I can see how developing a mesh of posts, comments and links will create a community around a specific topic. Everyone in the community will benefit from the conversation. And having links from many different sites back to your own site create a natural improvement in search engine ranking.