PrintScreen

PrintScreen is a tiny and portable application that can capture the full screen and automatically save the image to file. It can be handled with ease not only by experienced users, but also by beginners.

How it works

The program doesn't have a graphical interface. Double-clicking its .exe file or calling its process from a Command Prompt window sends the signal to take a snapshot of the full screen. The footage is automatically saved as an image file with the JPG format, which is stored in the same location.
However, you should make sure to move the graphic file to another directory or change its name before taking a new snapshot, since the existing file is overwritten by PrintScreen without asking for permission.

Portability advantages

The entire tool's packed in a single .exe file that can be saved in any part of the hard disk or copied to a removable storage device, in order to seamlessly run it on any computer without administrative privileges. It doesn't make modifications to the Windows registry by adding new entries, nor does it need DLLs or other components to work properly.
A traditional file deletion task is enough if you want to uninstall it. However, since it auto-creates saved images in the same directory and doesn't give you the possibility to set another destination, make sure you're not launching it from a write-protected or full disk device.

Evaluation and conclusion

It didn't hang, crash or display error messages in our tests. Everything worked smoothly. On the other hand, it's a bit inconvenient to use, due to its limited set of features. We must also keep in mind that PrintScreen hasn't been updated for a long time. Unfortunately, it doesn't seem to be in development anymore.