The University of Sussex has an amazing Learning Technologies team and website, including an A-Z of helpful apps for teaching and research. I met with a member of the team the other day, Anne Hole, who introduced me to a few of these tools, which I will be tinkering with in my teaching in the coming weeks.
One I began using immediately was ThingLink. ThingLink allows you to embed text, links, images, etc onto an existing image. It's perfect for explaining the iconography of a piece of art of emblem, which is what I used it for, but you can also use it for maps, diagrams, portraits or images of architecture. It's interactive, and can be crowd-sourced. You can share the items on your 'channel' for your students, or indeed the wider public.
Here are two of my early ThingLinks: Alciato's Occasio emblem and Holbein's Ambassadors.
What do you think of ThingLink?