This is most often done on an exchange basis. That is, you recommend good ezines and they reciprocate on their site. This works great because someone who has just signed up for one is ezine is very inclined to subscribe to other similar ezines. Ask subscribers to pass on copies of your ezine to friends and associates. If it contains lots of useful information then they will.
People like to pass on useful tips to friends.
Always include your subscribe instructions in every issue. This allows current subscribers to easily change the email they subscribed under. It also allows former subscribers to resubscribe when they come across an old issue. Finally, it allows those reading pass along copies to easily subscribe. Exchange ads with other ezine publishers.