If you want to read and collaborate documents, video and more, you can use a program like Box. You first go to the Box website and register your account. You then get a small spot in the cloud to hold your documents. Create folders, upload files like PDF and office files.
When done, go to your iPhone or iPad and download the app. Login, and you will see your files. Although you cannot edit on the mobile device, you can comment on. Then share it off to more to make it a full collaboration tool.