Reinvention of the wheel, or is a standard solution the best idea ever

In most cases, you can find a standard solution for quite all needs in IT development and testing. Besides that, discovering the continents again serves as bad taste, in case you want to develop such the same stuff you can “download from the internet”. But is this true for all situations? Is the standard solution the best choice ever? This topic I want to discuss, showing a couple of my favorite reinvented wheels.