imgpaste is a command-line utility that saves the (image) contents of the clipboard to an image file on-disk. It can be used after copying an image from a document or from the web, or after taking a screenshot (with the Snipping Tool via win+shift+s or via Print Screen). imgpaste supports JPEG, PNG, and Bitmap output file formats.
imgpaste was initially coded by Mahmoud Al-Qudsi during a live development session. The two-hour clip can be viewed on YouTube for a look at some of the challenges (and Windows bugs!) encountered during the process. The original code as of the end the live screencast is viewable in the git snapshot here for posterity and reference.
imgpaste is freeware released under the terms of the MIT Public License.