AdSense delivers text-based Google AdWords ads that are relevant to what your readers see on your pages. You get paid when users click on AdWords ads displayed on your site.

You cannot run other text-based ads on the same pages as the Google AdWords ads. This rule applies only to ads that "mimic the look and feel" of AdSense. For example, Amazon.com affiliate links are O.K.

Not allowed pop-ups or pop-unders that interfere with site navigation, obscure AdWords ads, change user preferences, or are for downloads. Other types of pop-ups may be allowed, provided that they do not exceed a combined total of 5 per user session.

Available text-based 468 x 60 banners, 120 x 600 skyscrapers, 728 x 90 leaderboards, 300 x 250 inline rectangles, buttons, more.

Google AdSense advertising network is being constantly updated with improved reporting features and channel filtering.

You are also able to change the colours of the text ads so that they either fit into the design of your site.

You are able to redirect any unpaid ads to a third party network.

$100.00 minimum payment. Affiliates are paid monthly, within 30 days of the end of month.

Besides English, AdSense publishers now have the option of placing their ad code on pages with content in other languages.

Accepts majority of sites without "excessive advertising".
Recommended.

Chitika

Earn money by displaying contextually relevant paid listings (eMiniMalls) on your website / blog feed. Display targeted products and get paid for clicks.

You can set your own keywords and products instead of contextually targeting products.

Chitika will pay you 60% of Chitika's revenue.

eMiniMalls offer a selection of standard ad formats for you to use on your site.

Chitika advertising network will make payments to your PayPal account. If you live in a country where Paypal is not accepted, just send an email and they will send you a check when your balance crosses $50.

Referral program - you will earn 10% of the CPC revenue that your referrals earns for up to 12 months from their approval date.

Clicksor

You need to embed a html code on your website. Whenever someone visits your site, your defined keywords will be replaced by a Clicksor link.

Furthermore, you can also display their text based banner in a selectable size.

You will be paid for up to 60% of the advertising revenues generated by your website. The advertisements are charged on a CPC metric and the actual rates may vary depending of the website performance and market conditions.

Has the feature to set the minimum bid price for CPC or CPM.

Payments will be made on the 25th of every month for the earnings of th previous month. Minimum payout of $50 via check and $20 via paypal.

Available referral program.

Kanoodle BrightAds

Contextual advertising network, similar to AdSense but worse targeted and pays much less.

Available all the standard ad sizes such as the banners, leaderboards, skyscrapers and rectangles.

BrightAds will pay you 50% of their revenue.

BidClix takes 50% of your cut.

Designed for all standard ad units - skyscrapers, banners, pop-unders, etc.

BrightAds pays on a net-30 basis, with $50 minimum.

Kontera

Another contextual advertising network

With ContentLink publishers generate revenue while advertisers reach their most targeted audience on a CPC (Cost-Per-Click) basis.

ContentLink is contextually relevant keyword that is discovered in real-time on a web page and is automatically turned into a link to the most relevant ad from among Kontera's advertisers.

To qualify for ContentLink your website must generate more than 500,000 page impressions per month and be content-rich with more than 50 words per page.

Kontera works with publishers in all content categories, including content such as blogs and forums.

Mails you a check within 30 days after the end of each calendar month if your earned balance is US $100 or more.

Miva

UK company that lets you include Pay-Per-Click contextual ads both alongside and within your content.

You can choose any combination of Content or InLine Ads for your website - so even if you already have advertising on your site you can choose the ad formats that will suit you, and deliver more revenue.

Miva lets you select a default keyword for each Ad. If some of your pages do not have enough text to match against (such as 'thank you' pages or pages of images) then Miva can still serve Ads from your default keyword.

Ad Blocking feature lets you block competitor Ads from appearing on your site.

At the end of the month pay balances over $25. You can choose to receive payments check or PayPal.

RevenuePilot

Affiliates receive 60% of what advertisers pay RevenuePilot per each click.

Provides with various linking methods (search box, text link, xml feed etc.). Only pays for traffic coming from the US, UK, Canada and Australia.

It is possible to check online how much a particular keyword is worth across the RevenuePilot Network.

Payments are made NET60 once your balance exceeds $25 dollars.

You can choose to be paid by Check or PayPal at no charge. Wire Transfers are available for a fee.

Yahoo! Publisher Network (YPN)

Provides pay per click contextual advertising and currently accepts only US-based publishers. Similar to Google Adsense.

You are not permitted to display ads from the other network on the same page at the same time as your Yahoo! Publisher Network ads are displayed.

Payment options: PayPal (minimum earnings required - $50), ckeck ($100), and direct deposit ($100).