PGP stands for Pretty Good Privacy.  Despite the modest name, PGP is the industry standard for securing personal data.  It is freely available from many places on the internet an offers the following features:

• File/folder encryption
• File/folder secure deletion
• Secure wiping of free disk space
• E-mail encryption
• "Signing" of E-mail (verifies it was sent by the indicated user)
• Secure Network Traffic

PGP is available for many Operating Systems and will work with any e-mail service, including web mail and AOL.