1. PPC Advertising Network
Google AdSense is most popular under this category, but there are also others. First of all, you need to sign up with the network and paste some code snippets on your website. The network will then serve some ads which are relevant to your website, and you can earn some money for each click.
The earning of PPC advertising is based on the general traffic levels of your website, more importantly, on the click-through rate (CTR) as well as cost per click (CPC). The CTR depends on the design of the website while the CPC is decided by the nice of the website. Mortgages, financial products and college education, for example, tend to be profitable niches, while tech-related topics are likely to receive a smaller CPC.

In addition, the source of the traffic can also affect the overall CTR rate. The one that comes from search engines, that's to say organic traffic, tends to perform well because these visitors are looking for something, and they tend to click on ads more often.
The following is some of the most popular CPC advertising networks:
•Google Adsense
•Yahoo! Publisher Network (YPN)
•Clicksor
•BidVertiser
•Chitika
2. CPM Advertising Network
Actually, CPM advertising networks is much like PPC networks. The only difference lie that you are paid according to the number of impressions, for instance, page views.
If there is a blog that generates 100,000 page views monthly displaying an advertising banner with a $1 CPM will earn $100 monthly.
CPM rates changes with the position of the ad and the format. Generally speaking, the better the network, the higher the CPM rate will be. And the closer the ad to the top of the page, the higher the CPM is.

And CPM advertising tends to work well on websites with a high page views per visitor ratio. Generally, you can get as low as $0.1 and as high as $10 per 1,000 impressions
The following is some of the most popular CPM advertising networks:
•Advertising.com
•Value Click
•Right Media
•Tribal Fusion
•Burst Media
3. Banner Advertising
Selling your own advertising space is one of the most lucrative monetization methods. The most popular banner formats on the web are the 728×90 leaderboard, the 120×600 skyscraper, the 300×250 rectangle and the 125×125 button.

4. Text Link Ads
Many website owners are still using text links to monetize their sites, though, some using the no-follow tag and some not.
The advantage of this method is that it is not intrusive. One can sell text links directly through his website or use specialized networks like Text-Link-Ads and Text-Link-Brokers to automate the process.
The following are some text link marketplaces and networks:
•Text-Link-Ads
•Text-Link-Brokers
•TNX
•LinkWorth
5. Affiliate Marketing
Affiliate marketing is a very popular practice on the Internet. Under this system you have a merchant that is willing to let other people, or to say Affiliates, sell directly or indirectly its products and services.
Affiliates can send potential customers to the merchant using several tools, from banners to text links and product reviews.
List of popular affiliate marketplaces and networks:
•Commission Junction
•ClickBank
•Link Share