Hi,
I have extended the plugin to support the region 'Amazon Auto' as a new region at admin and widgit level.
This uses the 'region detect' plugin to determine the actual region to use when a user accesses the widgit.
e.g. I can have an Amazon item for sale and have a single widget on my site point to the user's local amazon site (if it is supported by you as a region) and falls back on 'us' if not.
Supports all 8 of your types. Let me know if you want the updates to add to your code - they updates are straightforward.
Thanks.
http://wordpress.org/extend/plugins/amazon-widgets-shortcodes/
