Naming your emotions
It can be quite difficult to name emotions and some people are better than others at doing this. Whenever I am working with a couple where one is expressing how they feel and the other is finding it hard to respond to these feelings or express their own, I share this wheel with them. It is a great tool to facilitate conversations about the source of one's feelings and a relief to both parties to overcome a block in their communication.
I do not know who designed this and cannot attribute it to them but when I first saw it I got a little distracted wondering if the categorisations were quite right. I soon realised I was missing the point and that it is a thorough exploration of emotions in a very useful illustrative form.