Excel has the amazing ability to grow beyond it’s original programming with an “Add-in.” Add-in’s are basically mini-programs you add to Excel to expand it’s tools and options. For instance, there are add-ins that will sort your sheet tabs in order, add-ins that will display a stock market ticker in your worksheet, and add-ins that dramatically expand Excel’s analysis tools.
Some add-ins are free- go to the Tools menu and select Add-ins (Excel 2003 and prior). You will see a list of available add-ins, install them by simply checking the box next to their name.
You can also use add-ins from other sources- some are free, some are not- and they are available from many sources on the web BUT BE CAREFUL, add-ins may contain harmful code that can infect your computer, so only get them from trusted sources and always use anti-virus software to scan them first off. Most of these Add-ins are downloaded as zipped files, so you will need to extract them to a new folder. Go back into Excel and select Tools, Add-ins, then click on Browse. Navigate to the file you unzipped, click on the add-in file and Presto! New Excel.