Facebook, Twitter and LinkedIn are the defacto names which come to mind when anyone thinks of social networks or social media. These 400 pound gorrilas of the social networks have embodied what social means to the web. They have large audiences who are uploading millions of photographs and even more status messages and stories. But within this reality, an interesting phenomenon has been occuring over the last few years. People have been moving away from these platforms, to more specialised networks which meet their particular needs. None of these networks have as much traffic or volume as the big three, but it probably helps increase the signal to noise ratio. Find out more about some of these networks after the jump.
Dribble is a community for 
designers which works on a basic premise. It gets its users to answer the question _What are you working on?_ Dribble is a community open to anyone, but it best serves the creative types, who are able to share small shots (screenshots) that show thier work, and current projects. Dribble is an excellent community for design professionals and freelancers to get work, allowing them to share a creative portfolio of the designers, and through integration of in platform features like _Hire Me_ buttons. For non designers, dribble is a great place to just explore new designs, illustrations and a place to find good, unique design resources.
Polyvore is a fashion focused community with a strong focus on social commerce. Polyvore aggregates fashion items from mulitple online sources and creates a library of selectable items. Polyvore users create themed collages called _sets_ out of these fashion items which their followers are able to shop for when browsing these sets. Polyvore extends this ability to make sets to items beyond fashion items to home decor, which is more akin to the humbler beginiings of the network. Polyvore began with a need to help the two co-founders redecorate their home. They used the Yahoo pipes system to build the digital collages to help them compare their options.
Stack exchange is a growing network of specialised communities, which seek to serve interests of a very specialised and segmented communities. Stack Exchage operates in a standard way across all its sites. A user asks a question to which other users respond and provide answers. The community also votes on the quality of the answers and is also able to edit answers wiki style so that the answers can continue to be polished. Stack Exchange does not provide a way to answer questions if a community for that topic does not exist. They pride themselves on enabling answers from experienced professionals or users. Some of the more popular Stack Exchange communities are Stack Overflow, the first community and dedicated to programmers; Seasoned Advice, for professional and amatuer cooks; WordPress Answers, for WordPress developers and admins.
Quora operates as a question and answer site. And is probably one of the most popular sites on the internet. It is similar to the Stack Exchange in that it provides seperated topics and categories for users to ask questions in. However it is more forgiving in that it allows for more discussion form answers than Stack Exchange. It also provides users the ability to create topic groups.However that is not to say that they don’t emphasise on getting answers from professionals. Quora also gives users the ability to create blogs on the platform as well, as well as integrating with their social profiles to connect with friends on the Quora platform.
Path is unique in that they limit the number of people you can share your path or story with. Path places a lot of emphasis on the stories you share and with who you share them ultimately they tend to respect the quality of your network rather than the quantity.
Github is not a social network. At least not a social network in the same spirit as Facebook where the emphasis is on making friends and sharing. Github is a repository for open source projects and as such is a hub for developers to share their projects. Like Dribble allows designers to show their work, Github allows the same for developers. But it goes beyong Dribble in that it allows users to collaborate on development projects and discuss them using provided tools. But Github is not limited to just developers. People are also using it as a way to develop collaborative documents and in some cases it has also been used to crowdsource national level legal documents.
App.net began as a alternative to micro-blog networks like twitter. With a key difference. App.net would request that users pay to use the network, platform access starts from $5 a month. The reason for this was that App.net would not earn revenue through advertising or selling of users data. App.net functions more as an underlying platform. Apps are expected to use the App.net platform to provide the social experience, wether it is group messaging, sharing of pictures and videos or tell stories. Recently a lite tier has been added allowing users to invite upto 40 friends for access to App.net. These users can experience the network, with some limitations.
So there you have it. Some of the interesting vertical networks that are available to you today. Do let me know in comments if you use these networks, or let me know of others.