Photoscape is a free software which you can download. This software has many uses but the one which I really like is the ability to create photo collages and add speech bubbles. It would be interesting to hear how others would use this software. It is great for creating Digital Storytelling, comics, digital multimodal products and collages.

For younger children probably but to have a look use abcmathematics/abcmathematics to log in. If you like the site you can sign up.

Explore museums from around the world, discover and view hundreds of artworks, zooming in on art works, sharing your own collections

coud be useful for cross curricular between Art and Maths

the Wolfram Demonstrations Project is an open-code resource that uses dynamic computation to illuminate concepts in science, technology, mathematics, art, finance, and a remarkable range of other fields.