I almost feinted from awesomeness when I saw
http://designer.3ddotgameheroes.eu/
The potential of such a web application if you can load/save designs from other people... Then users could develop all kinds of in-game items xD and submit them for being used. The flash application on that website does not allow you to see what others made and you cannot load it to edit it. An application like that is like a standalone game! Go to the side, mess around a bit and make something. You could even craft a miniature building or anything ;P. The key to making this work is the save/load thing and browsing other people's ideas.
Yeh ... the potential ... sharing ideas, expanding the game over the web browser (or at least a part of it) ... music to my ears.
Let people share their creations on facebook.
Let them have stupid battles with it in a web-browser ... xD. And then use it in minetest whenever it suits you! xD.