I had an iOS App that allowed for isometric (triangle grid) based drawings. I recently rebuilt a much more powerful version for the web, with easy-to-drop-in shapes and 'sunlight angle' control. Along with many standard features from vector graphics editors such as text (but specially set up for isometric context). It also has a powerful undo/redo/history system and export to common formats.
A little crossword editor and share-by-URL crossword player. The Guardian's crossword UI was annoying me and I figured I could easily do better. So I did.
Actually several little projects around generating Voronoi tessellations and using as basis for 2D printable-art, 3D landscapes and 3D printable landscapes.
A completely rebuilt version of Pattern Maker for the web: make patterns from simple rules, share via URL and export as PNG or SVG; and create video loops.