The official T-shirt for the useR! 2014 R user conference (to be held June 30 - July 3 at UCLA) will be the result of open source contributions and reproducible research.
The organizers of the conference are soliciting designs for the official T-shirt — but there's a catch. The image on the front of the T-shirt will be created entirely with R code, and the R code itself will be displayed on the back.
If you've got an idea for the T-shirt, all you need to do is to submit your R code as a pull request to the official T-shirt Github project. The current design is the letter R filled with the phrases "useR!" "2014" and "Los Angeles." I'm sure there are better designs out there, so if you have one, go ahead and submit a pull request.
Github: user 2014 t-shirt