OK this is seriously cool, and a great real world application of OpenSim, the open source spinoff of Second Life: Subquark, an Australian development studio, used Sim-on-a-Stick to create 3D art for a real life card game, Mint Tin Aliens, which they developed. (As depicted above, and blogged about here.) Sim-on-a-Stick, as the name suggests, is a portable version of OpenSim, making it easy to create and transport 3D art files at an extremely low cost. (You could use Second Life for doing this, but thanks to SL's thorny IP rights, you'd have to create the 3D content on a simulator you were paying for, and make sure you had the underlying rights to the all the 3D content used in your 3D art.) For that matter, standard 3D modeling software tools come with their own high costs and licensing challenges.
This isn't a conjectural application, by the way, because this game actually already exists: "It was used for the final deck of Mint Tin Aliens and six copies of that game have already been sold," exlains Ener Hax, who did the OpenSim development.
See for yourself: