Here are the fundamental models most viable for the small business owner, ordered from simplest to most complex (sort of...). 
You can watch the 2-hour presentation on evaluating the different models for profit potential at: The Money is in the Model

Description: A 6-page site (aproximately), paid traffic. Landing page is long sales copy giving visitor only 1 option - "click here to order", which is an affiiate link to merchant order page.
Examples: chickenDIYguides.com,

Description:  A 12 to 20 page site at launch, traffic is paid &/or organic. May be long sales copy landing page + about a dozen article pages. The visitor typically has 2 options: to order the product or to read articles; usually "Buy Now!" is veryobvious and "articles" is less obvious.  Why do you think that would be?
Examples: bettafishcenter.com

Description: A 20 to 30 page site at launch reviewing 3 to 10 competing products in a narrow niche; buying any of these products pays an affiliate commission. Contains a review page summarizing all products, a page for each product with a detailed review, and many content and keyword rich article pages.
Examples: top10wowguides.com

Description: A blog with articles, advice, product reviews, possibly discussion on many specific topics within a clear niche. Often many monetization methods are used simultaneously, such as Google AdSense, affiliate links, banner advertising, direct product sales, and more. Most require over 100 pages to begin generating revenue.
Example: mamanista.com

Description: A site charging members a monthly fee for access to premium content. Usually several hundred pages are needed before charging for membership. Many are educational, perhaps delivering new lessons each month (either via emal or access to new pages). Requires constant updating with fresh content. Often there are two or more levels with free membership as the basic level. The free membership provides good content with frequent opportunity to upgrade to get premium content or to buy specific products.

Examples:
Affilorama.com offers a free membership with about a 10 hour course on affiliate marketing. Their premium membership is $67/month and offers additional training and tools for keyword analysis, link building and more. They have a very active and responsive forum where members and experts help out with problems and questions.

Wealthy Affiliate is a membership site that recently increased their price to $97/month (no free membership). They offer an 8 week affiliate training program, research tools, niche analysis, prebuilt sites, an active forum, and more.

Variation: Fixed Term Membership Site (FTM Site) [more detail here...]
Description: Identical to a membership site except that membership fees are no longer charged after a set period of time, often 6 months, 9 months, or a year.  This usually coincides with a training course. A 6-month course would charge a monthly fee for 6 months, then the membership is free to any members who completed their 6 months.

Examples:
BecomeaBlogger.com is Yaro Starak's 6 month course & 6 month fixed term membership site for teaching beginning and intermediate bloggers how to make money blogging. It costs $47/month.
BlogMastermind.com is Yaro Starak's 6 month course/6 month FTM for training those serious about becoming a pro blogger. It costs $97/month.

Description: A store front offering products just for a specific niche. It may offer anywhere from 2 products to thousands. Products may all be affiliate links, or the site may be that of a reseller offering products from many merchants (either from the reseller's warehouse or drop shipped from the manufacturer, or the site may belong to the manufacturer.
(Note: a niche shopping mall with only 1 product is actually a single product micro-site.)

Examples:

Dog.com is a large niche mall offering hundreds of affiliate products for dogs. It appears that this site owner is strictly an affiliate for all these products.

Chopperstoys.com is a storefront offering parrot toys all created by the owner of the site.