Developed by Emilio Gomariz and Kim Asendorf (under the guise MAADONNA), you can drag an image from your desktop into the page to be transformed into a matrix of animated icons. There are various sets including classic animated emoticons (both Western and Japanese) and sprite blocks from old Nintendo games (such as Super Mario Brothers, pictured above).
Similar to YATTA! is this piece which can convert your image into a matrix made up of Facebook icons (Webcam needed).
This webtoy takes Google Streetview photographic images and turns them into 'Little Worlds' style fisheye panoramas. It has even been used to create videos, here by Halcob
Made by Tim Holam, this tool allows you to draw with words, sentences and paragraphs. You can choose whatever text you wish to use, change it's colour, and save the results.
Fun webcam toy by Felix Turner turns your visual feed into a trippy 3D mesh, running on HTML5 in your browser (Note: Only works with Chrome and Opera).
Another webcam toy, this by Mr.doob (aka Ricardo Cabello) which turns the visual feed into pseudo-3D forms (Chrome required).