You can use the free foxit reader to fill in the forms, and if you pay a little you can design the forms that way you want.
You can also us iText to programmaticly create those forms.
There are free online services that allow you to upload a pdf and you can add fields also.
It depends on how you want to do the designing.
EDIT: If you use foxit reader, you can save any form that is fillable.
There is a setting inside the PDF file that turns on the allow saving with data bit. However, it requires that you have a copy of Adobe Acrobat installed to change the bit.
The only other option is to print it to a PDF print driver which would save the data merged with the pdf file.
UPDATE: The relevant information from adobe is at: http://www.adobeforums.com/webx?13@@.3bbb313f/7
When you use Acrobat 8, or 9, to enable user rights on a PDF so that it can be saved with the data, it adds about 20 kb to the pdf.
The other possibility is to use CutePDF Pro, add a submit button and have the XFDF data submitted to your self as an email or to a web server. The XFDF data can then reload the original PDF with your data.