Android: Hovernote makes it easy to take notes on your Android phone without closing the app you're already using. Just open the app to take a quick note, then save and close it when you're done.
Hovernote's icon floats on the screen in all apps. When you're ready to make a note, tap it to open a new note, even if you're in another application. When you're done, hit the minimise button and you'll go back to what you were doing. Hit the menu button to save the note to a folder or share it to other applications like Evernote or email.
It's easy to use, and the video above from GadgetHacks shows you exactly how it's done.