• Pop-up and pop-under ads
• Banner and graphic ads
• Text links
• Affiliate programs
• Co-registration

Putting ads for you site on popular sites within your genre is a very good marketing decision, search engines pay attention to theme and popularity.

Also, text links have grown in popularity over the past couple years since a link with the words "Discount Widgets" means more to the search engines than a graphic link with the same for it's alt tag.

Banners, pop ups, pop unders, and many other are collectively

internet advertising

. Whether you're the advertiser or the one publishing the ad, google adwords, fastclick offers solutions.

Publishers make roughly $10 per 1000-2000 visitors, the true number depending on a number of factors including ad size, text link, etc.

Another type of internet advertising, perhaps more importantly is link-building. A few links on popular websites, ones that are "on-topic," are a huge boon to an internet marketing campaign. There are other forms of internet advertising such as in-text advertising offered by http://www.vibrantmedia.com/. This is a largely unpopular form of advertising because it looks like a link and when you put your cursor over the link an advertisement pops up. So, the ad is on the same page as opposed to through a pop-up window but it doesn't even require a click the link. Check out this great article at Entrepreneur.com and notice the green double-underlined "links" on the page to see how ads are served using the technology Vibrant media calls IntelliTXT.