SharePoint and PowerShell: Get all Site Collections that are using Nintex

Really simple: Run through every site collection of a web application and compare the feature definition IDs with the GUIDS provided in the array. Of course you can change the GUIDS in the array and use this script for other features as well. And yes, you will get a tiny .txt at the end, remove the header and footer and use the file in Excel or in a SharePoint list!

SharePoint and PowerShell: Get all Site Collections by Template

SharePoint and PowerShell: Get Site Collections that are using InfoPath