I know this is the Moodle core forum, but I think this is worth to be announced here.
Actually, the EJS community is very active and a lot of simulations can be found and downloaded for free. The best place for this is the comPADRE digital library which also has a section for mathematical tools applications written in EJS.
EJSApp are a set of plugins for Moodle that let you:
1. To deploy applications written in EJS.
2. To control user access to the deployed EJS applications and distinguish between virtual labs (or simulations) and remote labs.
3. To set several resizing options for displaying the embedded EJS applets.
4. To backup and restore thanks to Moodle course backups.
5. To use cloud storage for any data, image or state file created by the EJS application.
6. To create sessions for synchronous collaborative working with the Java applets created with Easy Java Simulations.
7. To manage and control the access to EJS remote laboratories by means of a booking system that gets integrated into Moodle.
I'm sure you can find these tools useful since the combination of EJS + EJSApp modules offers a powerful and easy way of adding mathematical tools, experimentation and simulations to your Moodle courses.