We've talked about Pixabay before, I think, as another place to find public domain images. It's one of my go-to sources for images for presentations. It's even easier now to find and use photos in Word or PowerPoint by using the Pixabay Images plug-in for Office. If you need help finding and installing PowerPoint plug-ins, Richard has you covered with his video here.
For Google Docs, Richard has a post showing how to use the Pixabay and Full Deck add-ons. The Full Deck add-on is new to me and uses Unsplash that Kerri talked about last December.
Most recently, I used the Word Cloud Generator add-on for Google Docs. I had forgotten how much I like the visual representation of the important words in a discussion or exercise. Here's an example from a recent discussion about purpose.
While I haven't used this add-on yet, It's something to keep in mind when I need to use icons in my presentations. The Noun Project has "over a million curated icons" and they're now available through an add-on for Google Docs and Slides.
Google Slides doesn't have a large number of add-ons available yet. Luckily, one of them is Unsplash for Google Slides. It's very easy to use and makes adding images to your presentations a breeze.
*If you haven't followed Richard yet, you really should! And, if you missed him in January when he presented for the 2018 Wild Wisconsin Winter Web Conference, you can watch the recording here.