Google Keep is the ‘humble’ alternative for taking notes, storing them in the cloud, and synching them across all your devices. While its philosophy is precisely to stay simple and clear, the latest version of the Android client (3.2.435.0) adds a new kind of note: drawings, which you can create from scratch using various brushes, colors, and sizes.
The new icon with the marker will open the image editor, letting you draw whatever you want right on the screen, and even add extras such as photo captions and alarms. Besides being able to create them from scratch, you can also edit existing images. At the moment all this is exclusive to the smartphone version, although the saved results will appear on your other devices in the form of flat images.