A while ago, I realized I wasn't checking my Google calendar often enough, missing appointments and things like that. So I looked for some kind of widget to display the calendar on my mac, but none of them were to my liking. The ones I found were only visible in the dashboard, or then existed as a big global always-on-top window. So instead, I built a system for displaying my (and my GF's) calendars as a desktop background.
To make this work, I use IdleWeb and a custom webpage. IdleWeb is a screensaver that displays webpages, and has a convenient option to also set itself as the desktop background. Using a screensaver as a background is a hidden setting in OS X that can be terrible for battery consumption, but seems to be OK here, as IdleWeb isn't a CPU hog.
Finally, I host a static webpage on my machine that uses JS to read in, parse, sort, and display the private XML feeds for the calendars. This works pretty well.
Here is the (very cobbled-together) source if you want to use it or build on it. The only issue is that if the network is not booted yet, you can have problems where calendars don't load for a while.
To configure the code for your own use, find your calendar's private XML feed (as shown above) and fill it into where it says
[INSERT YOUR PRIVATE GCAL XML FEED URL HERE].
