I spent the last two days working on a little platforming game in javascript/html5.
http://i.imgur.com/uvuPiuk.png
http://www.file-upload.net/download-10118986/platformer.zip.html (the download link may expire in a few months, if lurkers later want a reupload then pm me)
To open the game, open the .html file. The debugging stats are enabled, so if you want to disable them, change the "debug" boolean to false inside the .html. This is nowhere near finished obviously.
This is pretty much the first time I ever did something like this.
This page was of great help, I just copy pasted from there and changed how I saw fit and now look where I am. :)
I'm really thrilled to add more things to my game. I was actually thinking about adding items that you can pick up and then use (ropes that you can climb down for example), bridges that shake when you walk on them, enemies, collectibles, NPCs, ... there is no limit. The only limit is my daily time and energy.