I implemented a version of Snake with JavaScript and Canvas a number of years ago. This weekend I cleaned the code up a bit and threw it up on the site.
It's dead simple (under 200 lines of code), and has hardly any features (no score keeping, no pause, no options), but I kind of like the bare bones simplicity of it. It diverges from classic snake in allowing the snake to wrap around the screen and having obstacles on the map.
Snake, along with Tetris, is one the classic games that I can pretty much always come back to. Every now and then I find myself looking for something quickly accessible and completely mindless that I can play for a couple minutes and it's suprisingly hard to find a satisfying implementation from first page search results. So now at least this one is available, always there and ad free.