Your introductory subscription of four issues (a $19.96 retail value) begins with the first published issue of green*light, currently scheduled to mail in August, and ends after four bimonthly issues are mailed to you. Sometime during this introductory period green*light will contact you with a specially discounted yearly subscription offer, allowing you to continue receiving green*light after the fourth issue. There is no obligation to buy. You may elect to receive the paperless magazine, in an easy-to-archive digital edition (the print edition will not be mailed).
Another magazine with a paperless online edition is E Magazine. They offer a free trial of one issue before you buy.
Please leave a comment if you know of any other magazines that offer paperless editions.
EDITED TO ADD:
Here's the motherload for digital subscriptions, NewsStand.com.