Free My PDF
Use this site to remove passwords and restrictions (such as printing, copying text, etc.) from PDFs.
Note: This only works for PDFs that you can open and read without any 3rd party plugins. PDFs that require a password to be viewed cannot be unlocked by this service. This is because this is not cracking. Viewable PDFs with restrictions are not really protected, no more than a door with a broken lock, as opposed to password-protected PDFs.