PDF Encrypt software is a very flexible and powerful program, PDF Encrypt software allows you to encrypt (using standard 40-bit or 128-bit supported by Acrobat Reader 5.0 and up) existing PDFs, set permissions, add user and owner password. For example you can encrypt a PDF without to allow to print it.

Advanced Encryption Package 2007 Professional
AEP20067 PRO most noteworthy feature may be its flexibility and military grade encryption: program includes 17 encryption algorithms (Rijndael, TWOFISH, BLOWISH, CAST, MARS, TEA, etc) to encrypt your files. It also includes file shredder. RSA supp.

CryptoHeaven for Mac OS X
Integrates online storage and sharing, email, instant messaging in one unique package. Provides real time secure communications for text and data transfers in a multi user secure environment. Unique secure group collaboration and more.

CryptoMite
CryptoMite enables you to encrypt, decrypt, and wipe files and folders of any type. It supports various encryption engines, along with zip compression. Functions to build self-extracting encrypted zip files and eMail capabilities are also included.

Outlook Express Privacy
Outlook Express Privacy lets you control access to Outlook Express and its email message database. When you enable protection, the program disables access to the message database and address book files.

ap PDF Encrypt
PDF Encrypt allows you to encrypt (using standard 40-bit or 128-bit supported by Acrobat Reader 5.0 and up) existing PDFs, set permissions, add user and owner password.