PE Encrypt 5.0
the author of this app says:
This program allows you to encrypt your important documents, passwords, sensitive financial information and personal data. You can even send e-mails with your secured, encrypted files safe from prying eyes. Even if your Pocket PC gets stolen or is lost, you can rest assured that your private files are safe.
PE Encrypt is also a fully functional file explorer. You can delete and copy whole directories at once and encrypt/decrypt files by simply clicking on them.