This may seem a bit off topic to many, but if you spend time in Microsoft Excel dealing with data (work at an engineering firm?) this is something that can come in handy. I came across this post on the website "TrumpExcel" by user Sumit Bansal and thought I'd share it:
Essentially, you can get the sum of different cells based on their color. Very helpful if you use cell colors to differentiate data. Surprisingly, this is something Excel does not do natively. I especially like his Visual Basic code for creating a back end function making it quick and easy to use over and over.