Hopefully your list targets individuals in an industry that your product provides a solution for. If that is the case, you are likely going to get between a 1-2% hit rate on emails that you send to your list. If you don't want the people on the list to get mad at you for spamming them, you should make your list opt-in, after the initial email.
You can use the list to get people to check out your website, your twitter account, your blog, etc... but a more effective way to engage the recipients of that first email might be a short webmonkey survey that offers a prize to a random participant of the survey.
You can use your email for a number of ways to generate some revenue.
For instance, for your restaurant, you can use it to send out coupons, or offer special promotions that only those who receive your news letter are privy to. If it is possible, you can create a database of Birthdays and offer a free meal for the celebrant.
For your consulting business, you can have a monthly newsletter that features tips based on your consulting services. If you are giving a speech, you can advertise it there. Personally, along side the tips, I like to advertise things like a new ebook that I published, or a webinar that I'm going to host.
I hope this helps...
I think the application of your list will determine the possibility of generating revenue with it. Are you providing your customers with information they cannot access without you? Or, are you providing them information that is EXTREMELY time consuming to compile, so they must pay you to do it for them?
The only way I could see someone paying for a mailing list is if it met either or both of the two above conditions. The revenue would probably be generated on a subscription basis... If you post more info we might be able to give you a more detailed answer...