This article will go into more depth about exactly what you can do with your e-mail list and how you can use it to maximum effect. The first mailing list thing you should do with your list is always ensure that when you create mailings that you do so in a targeted manner. Most e-mail marketing software options now come with some sort of segmentation ability built into the software.
Segmentations gives you the opportunity to create categories of subscribers, this will then allow you to segment particular users into mailing list specific groups e.g. "new subscribers", "active subscribers" or even "subscriber who have purchased previously". Be creative with your segmentation and deliver e-mails targeted very specifically to your particular audience.
Another tip that so many people fail to include in their e-mails is the option of forwarding the e-mail on to another user who may be interested in receiving more information about the particular topic you have addressed. Forwarding mailing list is a fantastic opportunity for a list owner to get their products or services in front of people who, without their connection to a member of your list, may otherwise have never heard of your website or what you're offering.