Maybe the bookmarking networks are considerably explored. Yet, most people don't even use the web for anything useful. All they want is already on Facebook galleries and those "social" networks. Bookmarking options are limited by its sources and most people sources are always the same, you just see what your friends say and your friends that belong to the same circles you do, often only see the very same things you do. I dare to say there is more communication than content. This may be the majority and it is very active but not very "dynamic" in the sense that social networks and chat problems don't replace each other just because they are better. People are tied with common interests and habits. Hard to change.
This is one reason why I like StumbleUpon and twitter and sometimes, even Chatroulette. What I can't find? Oddly enough, I can't find a good code snippet network. GitHub and alikes made a great step with code sharing for full projects. You can search for projects not code snippets. There are many snippet managers that help you managing your snippets. Your code snippets. There isn't much of a link between the previous two. A snippet manager that also allows to search for snippets in others code. I believe that there is room for success here for someone able to do a cross-platform tool combining the capabilities to manage and search/ share code and a good integration. This is a very active minority made of programmers that use their own tools and consider functionality over the most. There is technology for this, a public XML-RPC API, a website and some plugins for main IDE's. Imagine writing your code, find a problem you never solved before and, with minimal effort be able to search for very specific code samples that you can use to learn and even apply when appropriate, always without leaving your Emacs...
