This is a thing for Crowdfunding Backers to keep track of which crowdfunding campaigns still owe them stuff, and also graph how much stuff they've got coming, and how late it really is.
I was keeping track of all this stuff on an increasingly complicated spreadsheet, and every so often I remember that I develop websites for a living, and that any spreadsheet containing thirty lines of code in cell is past due becoming some kind of real program. So I spent a weekend doing this.
Do you really care? Magic and pixies. Specifically, PHP, MySQL, CodeIgniter, Bootstrap & Bootswatch