I stumbled across this wonderful thread while searching for images for the Favourite designed calcio jerseys post, and it was started by Italian members there as a thread for them to post their own Photoshop creations of their favourite calcio maglie. They go into quite a bit of detail, from using the proper logos of the selected team but applying it to different kit manufacturers, colours, styles, complete with new custom club sponsors.
Some of them are wonderful pieces of work, and in a lot of cases much better work than the real deals.
They appear in alphabetical order. Click for bigger size (name of the team in the file name – some can be hard to guess).