Here's one scenario I haven't started on and I just want to make sure my thoughts are correct regarding how to proceed.
For this example, let's say I have a buyer, a seller, and a product, so you can call me the middle-man.  Both the buyer and seller have accounts and I have all their information.  They "meet" over the purchase of a product.  To complete the transaction both buyer and seller need to sign off and then an invoice (or similar) is generated as a PDF.  The PDF needs to include stuff such as my logo, the logos of the buyer & seller, the product information, the signatures etc.  The information will be coming from multiple forms.
What I'm thinking is to make an Invoice Form for the transaction and use HTML fields to add in the logos and some sort of styling to make it look nice.  I then use one of the Formidable add-ons to create a PDF from the form.  I've attached an example that looks nothing like what I want :) , but at least it shows several of the ideas I'm thinking of.
Questions:

1. Does that sound reasonable?
2. What's the best and easiest way to style the output?
3. Is "PDFs" the only addon I'll need to accomplish this?

Let me know if you have any examples you would like to share.