E-mail marketing has been around a long time, and I would include safelists, bulk e-mail programs, and list builders under this category.  I've had pretty good success promoting with these tools; so you need to make sure this is part of your marketing arsenal.  Note: The great thing about Bulk email and List Builders is that you limit the amount of email sent to you; often safelists will generate tons of email so either invest in a safelist sender or be very selective.

Here are my top Email Marketing Programs:
Blast4Traffic - Great bulk mailer.  You pay a one time fee of $34.50 and you can mail to 2.3 million 100% optin subscribers every day.  Lots of great features, and you can save 20 of your advertisements.  They also have a pretty slick editor so you can make so pretty fancy HTML ads.  I've used this one for the past 3 years and have very good results.  You can also make money when someone buys a Pro membership you get 50% from the sale.
Your Lucky List - This is what I referred to earlier as a List Builder.  You will need to promote Your Lucky List to get people to signup under you.  Each week Your Lucky List randomly generates leads for you to mail to from within their website.  There are also Pro options that give you hundreds of leads without you having to promote, but promoting can also generate income from commissions when others upgrade to Pro, anywhere from 40% to 50%.  Highly Recommended.
Safelists - Safelists are optin often free to join email programs for promoting your business.  Usually they have a Pro option where you can either send more often or to a larger audience.  Some of the ones that I've used include:

Cash4uSafelist - Great safelist, doesn't overwhelm you with email, and a pretty decent subscriber list of 25,000 members.

Mad Vlad Safelist - Simple easy to use, and free to join.

Got Safelist - A pretty slick safelist about 15,000 members, but it does generate a lot of email to your address.
ListJoe - I joined ListJoe a few weeks ago and am already getting referrals with this e-mail list builder.  One of the great things about ListJoe is that when you get emails from other members you can click on a link for credits and then visit their websites.  By clicking on this link in the e-mail you are building up points that equate to people you can send your e-mail to.  It doesn't take long for you to build up 500 - 1000 per week.  ListJoe is absolutely free to join, has a downline builder in other e-mail programs, and you can purchase a Pro membership that allows you mail every day or two days depending on the option you choose.  Highly Recommended!
The List Auction - I just joined the List Auction and I am impressed.  As a free member you can send your email message to 500 people once a week, but it gets better because everytime you get an email from the List Auction you can click on a link and earn credits.  These credits can be used to add additional people to your list.  Even with the free option you can also earn commissions when those you refer upgrade.  They have a couple of Pro options Silver and Gold that I am looking at right now that allow you to mail more frequently and get larger commissions.  Looks like a real winner, and completely free to join and use.
JoeSacco.com - Your source for Internet Marketing Tools and Opportunities