In Pictures: 13 useful add-ons for Microsoft Excel...
Mini Calendar and Date Picker for Excel 2013
This app lets you embed a mini calendar into your spreadsheet that will make it easier for you or others to select a date to enter into the spreadsheet. The calendar can be customized to highlight specific dates, given different theme colors, or resized.
In Pictures: 13 useful add-ons for Microsoft Excel and Word 2013