Help with encrypting/decrypting columns at the database level

Can anyone help with suggesting ways (and giving how-to's) for encrypting table columns (eg, SSN, account #'s)?  The data needs to be kept encrypted from unauthorized users (eg, consultants who come onsite) and on backup tapes.  The encryption/decryption of the data should be transparent to the users who use the application and for user reports/queries that need to have that data.

I read about Transparent Data Encryption but that looks like it only used for backup tapes and Pluggable Encryption Technology seems too involved.  Is there a relatively easy way to encrypt and decrypt data within an organziation?