persian calendarpersian calendars in cf seem to have come up a bit lately and since monday was a holiday here in the big mango i had a few hours to put into slapping together something. you can see the first cut at a persian calendar CFC here. it doesn't do much except format/convert gregorian dates to the persian calendar and back again (right now it can only parse medium/short persian date formats). still lacks calendar math, real persian date string parsing, arabic-hindic digits date formats, etc.
so what's a persian (or iranian) calendar? why it's the formal calendar in general use in iran, also known as the solar hijri calendar and sometimes as the jalali calendar. i've also seen it described as the shamsi calendar. frankly i have no idea which is correct so i'll stick with "persian". since it's one the few calendars designed in the era of accurate positional astronomy, it's probably the most accurate solar calendar around. you can read more here or here.
i've also been looking at this java calendar class. it has a boatload of calendars (besides persian it has mayan, nepali, hindu, coptic and believe it or not a french revolutionary calendar).