Automatic SKU generation

I've created an extension that inserts an SKU nr into the SKU. You can prefix and suffix the sku which makes the generator start at 1 for each unique prefix/suffix. Upon the subsequent usage of that prefix/suffix the next increment will be inserted.

You can read more about it here.
http://www.contao.org/extension-list/vi ... tosku.html

Next version
This is just a first version with the basic functionality. I'd be interested in what I can do to improve the extension, so ideas are welcome.

For example: I'm thinking to add a standard prefix/suffix per product type. So you can type # for sku and get the correct next number with whatever the prefix is so you cannot type it wrong.