We are building a comprehensive database of Excel Add-Ins. It's hosted on the Silk.co data publishing platform. Silk is a simple visually-driven database that allows anyone to function as a DBA and build interactive databases and mini web-apps from simple spreadsheets. We're adding new Add-Ins all the time.
Why are we doing this? The Silk datateam lives in Excel. But as powerful as Excel is in crunching your numbers, there are limits to what the spreadsheet application can do. But that's what add-ins are for. Add-ins (the downloadable ones that don't come pre-installed) are small software patches that enhance your Excel functionalities with additional commands and features.
While Microsoft offers various add-ins, anyone with basic coding skills can create and share Excel add-ins. This database offers an overview of the downloads on offer. Far from exhaustive, this should be regarded as a work-in-constant-progress, with regular updates. If you want to submit more Excel add-ins to be included in this database you can use this form.
About Silk.co: Silk is a free tool that let anyone quickly and easily publish data online. Silk converts tables, spreadsheets and Google Sheets into full web databases with a simple importer. Each row is rendered as a Web page with the data values for each row intact. Silk users and editors can easily build a variety of visualization types (including maps, charts, image galleries, tables) using the data from the pages. Those visualizations can be published in Silk or embed in other Web pages. Here's a video explainer.