Freeware à la Folderico, but for file types [Custom icons]?

Folderico lets you change folder icons to whatever you want, which is great, but I haven't been able to find a similar software for file types.
I'm not looking to change the icon to every file, only certain ones that have blank thumbnails (think .bin or .gba files for example; I want to give each .gba file a custom icon, like a game cover or something, but I don't want all the .gba files I have to have the same thumbnail).

Know any software like that?

Stardock IconPackager is not free but it does allow one to change file types among many other types of icons.

Thanks, I enjoy making photo realistic icons. I had a collection of XP icons I used to make and sell until Vista came out and now I am in the process of making Vista/WIN 7 type icons. I think there will still be a demand even when WIN 8 comes out. My only concern is that I have to go to the internet to transform images into icons (I had in-house software beforehand). Maybe I'll ask on the forum if anyone knows of any software that does this, pirate.