There are such programs about which we can say that they are "elegant", not fancy, not super—beautiful, but simply and understandably elegant. If you need a nice simple program for maintaining a personal calendar, then be sure to pay attention to MonoCalendar, written by a man with the Russian name Boris :)
The author does not hide that he drew inspiration from the Apple iCal product. I have seen this program under OSX and I think that the author has managed a lot. I'll run through the functionality that is most important to me personally:
The program also has drawbacks that can be considered children's diseases. For example, there are no reminders and cyclical events. I also really miss the import/export of online calendars in iCal format, which Apple's product is famous for.
I would like to wish the product rapid growth, and I recommend you, dear readers, to take a look at the product to know what "elegant" software is. By the way, the MonoCalendar distribution takes only 251Kb, but it needs Microsoft® to work.NET Framework/