In the domain of computing sciences, we use online IDEs to write and compile code. When teaching Computer Science, it's helpful to leverage these cloud compilers so students can experiment with code. The site Trinket.io has a great feature for that as demonstrated below.
Press the "►Run" button to see the software run.
A lot of instruction is delivered (or complemented) by video. Most video hosting solutions like - YouTube and Vimeo - have ways to embed the content in a webpage. Look for the "Share" or "Embed" function.
Google Maps has some pretty potent abilities - from collaborative contributors (like photos from summer vacations) to charting out points of interest to GIS data, there are a lot of functional ways to use Google Maps.
There are hundreds of different widgets that are available for web designers. Consider this example of a star rating system; educators could embed a rating on every piece of content they have, and students could leave feedback. This would help faculty understand pain-points in their courses.
Note that the star system
Embedding podcasts can help educators provide enrichening content for their students. There are thousands of high-quality podcasts that educators can use for both professional development and for student consumption.
This episode of Teaching in Higher Ed features Robin DeRosa, and speaks to open pedagogy.
There are a lot of reasons to embed Google Docs (or Sheets) into a website - namely, it makes it easier to modify content for end users. Leveraging the power of collaboration, learners could contribute to the knowledge base by adding their perspective and experience to an OER. The class could take shared notes in one document. Content from the teacher could be commented on by the learners.