Allows you to capture and save references.
Evernote is good for keeping your notes, and sync them between your devices. You can attach tags or documents to notes.
Zotero is a better solution. Installs as a plugin for browsers. It allows you, when on Google Scholar, to bring up a list of items on the page, select what you want and it’ll add the info to a folder, with all the bibliographical details it can find. You can then get it to create a bibliography in a format you choose. You are also able to add notes or tags. It will also sync the information to all of your other devices .
In Word or Open Office you can also get an add-on to add footnotes to your documents.