Google Forms are great for quick surveys and even quizzes (provided you don't need answer checking/feedback). SurveyMonkey isn't hard, but the free version has certain limits, and Google Forms is even easier to get up and going.

YouTube live streaming can be a way to hold an synchronous class session if your LMS doesn't include that feature. While it takes a bit of effort to set up, once you do it can be a decent way of having live video with a corresponding real-time chat. It can also be made private/unlisted.

I saw a presentation from NEIU librarians who discussed an Edit-A-Thon they held. It can be a good way to each students about the way information is generated online, and also can be used to teach research practices (such as correct use of citations), among other things.