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.