Cost: Free for the basic version; $5/month for the premium version, which shuts off ads, includes a PIN lock, boosts the monthly upload limit and enables PDF searching.
Available on iOS too? Yes
Evernote helps you stay organized across your various devices, from desktops to smartphones. Evernote lets you take notes, capture photos, create to-do lists, and record voice reminders, and it makes all of these things completely searchable. This app helps you sync all of your notes across devices. The search feature even lets you search for text inside images. The Web Clipper add-on lets you save anything you see online, including links, text and video, into Evernote with one click.