I love designs which make people feel competent, in control.
This is a DE coffee machine:
And it has little half-moon shaped guides for keeping a cup.
This gives a solid, physical indication to the user about where she should keep the cup. Many machines have round markers, but nothing physical. And it has happened with me at least once when I placed the cup wrong, and some of the coffee fell out. Possibly because I was tired or distracted. And it made me feel I was not in control.
This is why I find this little idea inspiring, when you can feel the touch of the bar on the cup, you know the coffee is going to fall in the right place and hence you feel in control.