The basic version of Evernote is a free web based organizational tool that allows the user to create notes, to-do lists, bookmark web content, snap photos. It syncs all content across your devices. The upgraded version offers additional options.
Get Pocket is a free cloud based bookmarking program. You can save an article or site easily to read later. It works on all platforms, and syncs between all your devices.
Symbaloo is a free cloud based platform to organize web content into tiles. The platform can be used as a homepage, or as a means to curate and share websites. It's very useful with students, by providing them specific sites for them to explore.
Awesome Screenshot is a free application that enables you to capture screenshots of a portion or an entire web page. You can save the images, annotate, save and share them.
Diigo is a free cloud based bookmarking and knowledge sharing too. Bookmarks can be saved in an organized structure and can shared with others. In addition, you can annotate online documents, highlighting text and taking notes. All are saved in the cloud.
Dropbox is a personal cloud storage service that is also used for file sharing and collaboration. Teachers can share files and folders with parents and students - which makes Dropbox a portfolio creation tool as well. There a basic free version that provides 2Gs of space.