Everybody loves to put their favorite pictures on their desk and have other people comment on them. MyCalendar attempts to do just that, but there are some downsides to using this extension.
When you install the MyCalendar extension, you access the extension through the Tools/MyCalendar option on the pulldown. If you wanted to customize the calendar, you can't. You'll notice that no options are available for this extension. Since we are selecting our graphic, this should've been a required option for configuring MyCalendar.
If you want a customized graphic, you need to copy the graphic into the root of your hard drive, rename the graphic "mycalendar.jpg," and then click on the MyCalendar extension. If it wasn't named properly or don't have a graphic, you'll just see the calendar itself without a graphic.
Another downside with the extension is that the graphic has to be a certain size, roughly 320x320. If it isn't 320x320, the image tiles (uck!)
A couple of recommendations to the author is to right-align the images so you can see the image AND the calendar, an options dialog box for configuration, allow the window to resize when the picture is loaded, regardless of the image size (of course, there will be limitations), and allow some custom CSS styles to spice up the calendar (looks kind of drab).
This is truly a good idea, but the extension lacks some fundamental features. If the extension is updated properly, MyCalendar could be a welcome addition to the Firefox extension family.