Although MPS comes with a rich set of languages so you can be a productive programmer or language designer from day one, the modular nature of MPS allows languages to be shared and combined freely. This page holds a list of additional languages that you may find useful for your applications.
MPS without any extra add-ons supports generating code into these languages:
MPS comes with a set of sample languages, both standalone and Java (BaseLanguage) extensions. They are typically located in your home folder in a folder named MPSSamples.version. MPS offers you a quick way to open them through the welcome screen:
Languages defined in MPS are typically distributed as packaged zip files that can be imported as plugins either into MPS or IntelliJ IDEA. Some language authors have published their languages into the JetBrains plugin repository, from where it is extremely easy to pick them up and start using.
The Using MPS inside IntelliJ IDEA page and the Building MPS language plugins page will give you details on how to import the language plugins into IntelliJ IDEA and MPS, respectively.