Settling Sibling Arguments with a Calendar

Although I'm blessed with three amazingly well-behaved kids (really!), our house still has its share of sibling arguments.  There is always fighting over which book to read, which show to watch, what color cup each girl gets, who brushes her teeth first, etc., etc., etc...  I've found a (hopefully long-lasting) solution to some of these arguments by letting each of the girls (L and E are 3 years old) get a 'special day' on the calendar.  When it's a girl's 'special day', she gets to go first whenever we take turns and gets the first choice of books/videos/toys/food.  For those random sibling arguments over toys, unless it's clear who took the toy away from whom, the 'special day' will settle the dispute.  Even my husband will ask the girls whose day it is when they fight over something.  We've been doing this system for a week and a half now, and it's working really well.  I've actually observed the girls saying "let's look at the calendar" to each other so they can see whose day it is.  They know the turns alternate so they acknowledge that if it isn't their special day today, they'll have their day tomorrow.  I can't take credit for this idea because I'm sure I heard about it somewhere, but I'm very excited about how well this is working, and wanted to share!