Draw.io is a simple but powerful online drawing tool with a raft of useful features.
Here’s an example of the kind of thing you can produce:
And you can visit the the live, interactive, html version here.
Draw scalable diagrams and designs with this powerful vector graphics application – Gravit.io.
Draw on a background and download as a jpeg. Graffiter is that simple.
Construct amazing images like the one below … and perhaps even explore the relationships between the variables using Inspirograph.
Vector-based online drawing application Vector Paint provides a simple way of creating scaleable images.
The Pulp-O-Mizer will help you design a retro-style 1950s pulp magazine cover.
Upload an image and change it into a work of art, or type in a few words and turn them into wonderful 3D text … all in a few clicks using Picture 2 People.
And here’s just one example: