You can always get a free 7 day Trial for Showtime. However, when riding a NYC subway the other day, I noticed an ad for a 30 day free trial. To get the 30 days free, simply go to the usual Showtime website and click on the normal "Start Your Free Trial" which is the usual 7 day trial. It will then ask you to set up a user id and password. After that, it will bring you to a screen to input your personal info. Near the bottom of the info, there is a field PROMO CODE. Click on APPLY PROMO CODE. Then in that field, type in promo code SUBWAY and then click ok. If successfull, you will get the following message "Promotion Applied! Enjoy your extended 30 day free trial!". Now since I live in NYC, I don't know if they tie in the validity of the promo code to the zip code you enter or if it will work for anyone not putting in a NYC zipcode.
Obviously, for new customers only. Cancel anytime before the trial is up. You will not be billed until the expiration of the free trial.