Esopo is a project to create a series of poetically or literarily interesting esoteric programming languages. Some of these languages can be used for practical or artistic purposes; some are just silly. For a complete description of the project (and the reasoning behind it), check out my post about it.
Eventually, all of these languages will be implemented via Javascript interpreters to allow people to play with them online. If you create something interesting using one of these languages, submit a pull request, and I'll be more than happy to post it as an example here.
Most of the original work on Esopo languages was hacked together in (fairly ugly) Python, and the language specifications are pretty informal. I'll post some of the Python interpreters here, but I plan to replace them with more carefully coded Javascript interpreters as soon as I can.