There is no official standard for what makes something “Web 2.0″, but there certainly are a few tell-tale signs. These new sites usually feature modern web technologies like Ajax and often have something to do with building online communities. But even more characteristic among these brands is their appearance. Web 2.0 sites nearly always feel open and friendly and often use small chunks of large type. The colors are bright and cheery — lots of blue, orange, and what we jokingly call the official color of Web 2.0: lime green.