Microsoft has added a new feature to Popfly – an easy to use GUI Game Creator. You can create most of the simple arcade games. The game creator has some pre-built game templates and hundreds of images, animations, backgrounds, and sounds to use in the games you create, and, of course, a way for you to write code if you reach the limits of what the user interface can do for you. Since this is Popfly, you can still save, share, and embed your creations everywhere from your blog to your Facebook page to your Windows Vista Sidebar.
I have created a game with one of the templates: http://www.popfly.com/users/sujeeth/Baby%20Crossing