I received an email from Sony for a free $5 SEN credit when signing up for a 30 day free trial to Music Unlimited. It states that it is only valid for email recipients, so check your email to see if you received it. You do have to enter a credit card, so make sure to cancel before the 30 days if you don't want to continue the subscription.
Here is a link to the email:
http://ebm.email.sonyentertainmentnetwork.com/c/tag/hBSqlUOB8y-RzB82jZ7AAP0CzYE/doc.html?t_params=EMAIL%3D
Here is a link to the email:
http://ebm.email.sonyentertainmentnetwork.com/c/tag/hBSqlUOB8y-RzB82jZ7AAP0CzYE/doc.html?t_params=EMAIL%3D