At my day job, we use Microsoft Excel spreadsheets as a pseudo "specification document" (spec sheet) for the websites, which are actuarial in nature, we create. At the time (several years back), since we chose Excel, obviously we needed an add-in for the few automated processes we supported and we needed something immediately (you know how it goes in small companies). The easiest way for us to create the add-in we needed was to create an Excel add-in file (*.xla). My background (5-6 years ago) was from VB6 anyway, so even though I'd switched to C#, VB6 was still fresh in my mind and writing VBA was a breeze - whether the code was clean or not, I've got not comment ;). I've recently made the decision to migrate an existing Microsoft Excel Add-In (*.xla) file to managed C# code. There were several motivating factors to this decision along with almost as many speed bumps... [More]