Microsoft Excel's conditional formatting is a wonderful "automatic" feature that allows you to formats cells based on the value of those cells or the value of the formulas in those cells. For example, you can specify that all the sales totals in your spreadsheet that exceed $5,000 are highlighted in yellow; or all the dates prior to the current year use a dark-green font; or use a shape or ratings icon to flag all duplicate values above 12,000. The options are endless and, in addition to all the preset formats, you can create your own custom formatting rules.
The best thing about this feature is that it provides a quick snapshot of your spreadsheet when you view it or show it to others. Because the formatting is based on values, you don't have to do anything to make it work except update your data.