Perfect

Exactly what I needed — a quick way to view a calendar without having to open or switch to an app. I use Outlook for my calendar, and if I want to just take a quick look at a calendar , I have to switch away from whatever I’m working on. This app overlays a calendar on the desktop, so it’s just a quick gesture on the trackpad to expose the desktop. Looks great and highly configurable.

The calendar can apparently link to your Apple or Google calendars and display appointments, but not Exchange calendars. That’s ok for me, because I was just looking for a simple, uncluttered view.

Carpevita about Desktop Calendar Plus, v1.3.5