I think a useful feature would be to allow users to embed a text string into their original document and have PDF creator convert them to editable fields.
For example as a document could have 'sig, rd="Customer Name",h=60,w=200,d="Please type you name"'
This would generate a PDF input field in the output document with a height of 60 points and a width of 200.
The position on the page would be the location of the sig text.
You could use the same principle for a number of other input fields including digital signature.
If you are interested in exploring the idea I would be happy to speak to R&D or marketing.
Regards
Dave