Not just skins, skinobjects widgets and more!
Skinobjects: Each one of 2DNN's skins ( designed or converted ) comes with a collection of SEO optimized skinobjects for module-title, page-title, breadcrumb and a number of other helpful skinobjects for easier skinning and administration.
Widgets: Widgets are used to add client-side interactivity to a skin. This includes sliders, galleries and more, because of the way this is set up its very easy for any page editor to add interactivity to a page. This can be used in any module that allows HTML input.