We live by the imac calendar (although we're shopping for a more elegant option). We publish the things we want others to know about, and keep some things to ourselves. We have family that helps out, especially on Saturdays when I work, which makes it all possible ( I recommend living in the same town as your in-laws if you provide them with their only grandchildren!)
We try to keep strict limits on how many activities kids can do. That said, it's spring, which must mean soccer in three locations, one of which I coach, baseball for two kids which hubby coaches, and marathon training for us, it gets crazy.