Site with lots of simple interactives from a variety of subject areas. Science and Math interactives are mostly for secondary students, but some Language Arts and History interactives are for younger students. These would be good for introductions to a unit/lesson or serve as a simple diognostic or review to check for understanding midway through a lesson.
Create digital pop up books online. Books can be embedded on other websites, viewed in 3D or augmented reality mode, and customized using your own images, artwork, and sound (premium version only).
Could be a really nice way for students to publish writing, create digital stories, or create stories to share with digital penpals.