Lisa Nakamura has suggested that customizable avatars in non-gaming worlds tend to be biased towards lighter skin colors and against darker skin colors, especially in those of the male gender. In Second Life avatars are created by residents and take any form, and range from lifelike humans to robots, animals, plants and legendary creatures. Avatar customization is one of the most important entertainment aspects in non gaming virtual worlds, such as "Second Life", IMVU, and Active Worlds. Many virtual worlds are providing users with tools to customize their representations, allowing them to change shapes, hair, skins and also genre. Moreover, there is a growing secondary industry devoted to the creations of products and items for the avatars. Some companies have also launched social networks and other websites for avatars such as Koinup, Myrl, and Avatars United.