Livebinders is a site I've been playing with for a while. Livebinders acts as a virtual 3-ring binder for you to organize your materials in. Each item can be in a tab or sub-tab in the binder you create.
You can store webpages, PDF files, images, text, videos and more into the pages of the binder.
There is a "getting started binder" and example binders on the site that you can use to get ideas and get started.
I'm using Livebinders to organize all of my lesson materials, as well as professional development resources and my presentation materials. As a former engineer, I used lots of 3-ring binders to get organized. Now I can do it virtually.
Below is an example Livebinder for a physics class, showing the content and tabs. You can view the original binder here.