10th, 11th and 12th WAY

10.Premium Content
Some websites and blogs give away part of their content for free, and charge for access to the premium content and exclusive tools.
SEOMoz is a good example. They have a very popular blog that gives advice and information on wide range of SEO related topics. On top of that visitors can decide to become premium members. It costs $48 monthly and it grants them access to guides, tools and other exclusive material.
11. Private Forums
While the Internet is populated with free forums, there is also the possibility to create a private one where members need to pay a single or recurring fee to join.SEO Blackhat charges $100 monthly from its members, and they have thousands of them. Obviously in order to charge such a price for a forum membership you need to provide real value for the members (e.g., secret techniques, tools, and so on).
Performancing also launched a private forum recently, focused on the networking aspect. It is called The Hive, and the monthly cost is $10.
These are just two examples. There are many possibilities to create a private and profitable forum, you just need to find an appealing angle that will make it worth for the members.
List of popular forum software:
vBulletin
Simple Machines Forum
phpBB
Vanilla
12. Job Boards
All the popular blogs are trying to leverage job boards to make some extra income. Guy Kawasaki, ReadWriteWeb, Problogger… you name it.
Needless to say that in order to create an active and profitable job board you need first to have a blog focused on a specific niche, and a decent amount traffic.
The advantage of this method is that it is passive. Once you have the structure in place, the job listings will come naturally, and you can charge anywhere from $10 up to $100 for each.
List of popular job board software:
JobThread
Web Scribe Job Board
SimplyHired Job-o-matic
Jobbex