Also a nice feature, which unfortunately not a lot of applications use, is the haptic feedback. E.g. when you drag an object in OmniGraffle, you will feel very subtle feedback in the trackpad when two objects align.

Almost 20 years ago I had a cool Logitech mouse that did this. The mouse had a haptic (Synaptics, I think?) engine in it, and when you moved the cursor over buttons, menus, or other UI elements, it would give a slight “tick” as you crossed each boundary. It was very cool. There was a lot of customization available for it as well.

I had to ditch that mouse when I switched to Linux. I think it didn’t have any standard HID-type driver or something.