I started using Jing over the summer, and have found countless uses for it personally and professionally.

Jing can be used to create a screencast or a screenshot.  Screenshots can be drawn on and annotated to highlight information, or give more detail.  My number one use of Jing has been giving teachers a visual guide to something that would normally be a long list of steps. Below is an example of a mid-year review that I needed my teachers to sign off on.  Rather than create word based instructions, I sent this Jing.

Teachers found it to be very useful, and it exposed them to a new tool they could be using in their classrooms.

Jing also allows users to create screencasts.  I use screencasts all the time to walk users through more complicated computer processes (see screencast below in my post on using Google Forms for walk-through observations).  The free version of Jing allows for up to five minutes of recording.  This seems like a lot, but five minutes goes quickly.

I hope you find Jing as useful as I have.