Although Excel can do amazing things, it cannot do everything. Plenty of niche industries need more functions or more specialized operations than what is available in Excel.
Sometimes, someone recognizes a common need. After seeing dozens of questions in Excel newsgroups about converting uppercase to lowercase, for example, a developer might offer an add-in to make that task easier than the current five-step process.
Literally thousands of add-ins are available for Excel. This chapter is by no means a comprehensive list of available add-ins, but it contains some of my favorites.
Jon Peltier’s website has always listed bizarre techniques for coaxing unusual charts out ...