In case you didn't know, for almost 1 and 1/2 years I have been
addicted to one MMOG: Second
Life. What separates SL from other games such as There, World
of Warcaft and others is that whatever you create within SL, you
own it and therefore can sell it. This has engendered many in-world
businesses and business models to flourish, including open source.
Even I've gotten into the business act. 
I've opened up a store on the newly created sim Ama Gi(which is ancient Sumerian for "freedom"), an island sim dedicated to the ideals and promotion of FOSS and free culture. My store is called simply "Antonius Misfit's Open Source Shop", where I sell some skyboxes, but mainly scripted "laptop" computers(all open source, of course). My latest creation is something still in development, but I'm very proud of it as it is my first product from scratch. It's a GPLv3-licensed build packager and rezzer I call "Apt-Rez". Of course, Apt-Rez isn't the only product of it's kind available(such as Rez-Foo and Rez-Faux), but I feel it perfectly serves as not only a ready-to-use solution for builders, but also as a learning aid for budding LSL scripters or a starting point to roll your own rezzer. Plus, Apt-Rez is also available for purchase either at my shop or on SL Exchange for a nominal price(Yes, the GPL says it's perfectly acceptable to sell your own open source items as long as the source is freely attainable, something that apparently even some open source developers haven't grokked yet).