Graphic Design Forums are a great way to network with other people in the same industry as you. They provide a perfect platform for you to ask design-related questions, find advice on all aspects of freelancing/running your own business and tender for new work.
They are a great place for you to obtain critique of recent projects and for you to offer your own advice and experience where you can. If you are not a designer but are looking for design-related services, such as: logo design, illustration, design for print or website design to name but a few then they are a great place to find professionals and obtain quotes.
Started in 2008, the GraphicDesignForums.co.uk has grown considerably over the last few years with over 6,800 members (as of 2013). The forum differs from most others as it only accepts members with a UK based IP address, ensuring all discussion/advice and assistance is UK related. The forum has many sub-forums on a variety of topics, from general graphic and website design, to SEO and business. You will find very friendly UK based members and as a result of their IP restriction, pretty much zero spam and in turn, quality posts.
Started in 2007, the DesignForums.co.uk is another forum that is mainly UK targeted, although it does have many other members from around the world. With over 6,500 members (as of 2013) this is another popular forum with a friendly atmosphere. Any spam is dealt with quickly by the resident moderators and there are already over 93k (and counting) informative posts to choose from.
Started in 2007, Estetica Design Forum is a large forum accepting members from all over the world (although a fair proportion tend to be UK based) and as a result, discussion is varied and may not always apply to you dependant on where you live. The forum is very popular and has a whole host of sub-forums covering many topics. Estetica is by far the largest forum with a whopping 67k members (as of 2013), although only a proportion of those will be active.