Yesterday I found MonoCalendar, a Windows.Forms-based calendar application, very similar in spirit to iCal.
MonoCalendar is a big exercise in abusing System.Drawing, when I ran it in the morning it was crashing. Just as I was preparing to file a proper bug (and after nagging Massimiliano to look at the crash) Sebastien, Bill Holmes and friends had fixed the GDI+ issues that were stopping MonoCalendar from running.
here is a screenshot:
To run it, you must be using the latest versions from SVN of Mono and GDI+. Hopefully we will have a new beta of Mono soon (1.1.16).