pdfcrypt allows you to encrypt a PDF (40 bits and 128 bits), set permissions, add user and owner password.
For example you can encrypt a pdf without to allow to print it. The button to print the file will be disabled in Acrobat Reader application.
jpg2pdf is a very flexible and powerful program. It can convert a collection of jpeg images into a unique PDF.
Put a free download button on your own website
Support txt2pdf, just copy+paste this html: