Many people have started using Google's AdSense program, but there are some who find it a bit too uncertain or simply not suiting their own requirements from an ad program.
But thankfully for such people, there are many alternatives to AdSense which attempt to alleviate some of its shortcomings. Here is a list of the most noteworthy ones from the lot with a description concerning each one.
AllFeeds (https://allfeeds.com/apply/)
AllFeeds has a great pool of online advertisers to choose from. It also features many display formats that you can choose from. These include banners, buttons, XML feeds, DHTML pop-ups and so on. It also features real time reporting of your ad status. The site will mail a check every month, provided that you earn more then $25.00, while rolling over earnings for the next month if you don't. Another interesting thing about AllFeeds is that it integrates with Google AdSense, maximizing your earnings with AdSense.
Bidvertiser (http://www.bidvertiser.com/)
Like AdSense, Bidvertiser displays text ads in your page. But the difference lies in the fact that advertisers bid over your advertising space, ensuring you earn as much revenue as you possibly can. This also means that bids will increase over time, earning you even more cash. You also get a great way to customize your ads with a very easy to use tool and detailed reports on your site's status.
Vibrant Media IntelliTXT (http://www.intellitxt.com/site/web_01a.html)
Vibrant Media IntelliTXT offers user-activated ads, highlighting certain words within the content of the page and presenting relevant ads when a user hovers his mouse over them. It uses a pay-for-performance pricing scheme and can easily be used along with other advertising methods, because it is unobtrusive. It places you in full control, allowing you to easily integrate it within your site with some simple JavaScript.
Nixie (http://www.nixxie.com/display.php?section=Partners)
Nixie claims to hold a technology that can read and understand your site, enabling it to display the most relevant content to your site. Besides text ads, Nixie also features price comparison listings as well as live auction advertising. It's very easy to implement and has a good payment policy as well.
MIVA AdRevenue Xpress (https://www.miva.com/partners)
MIVA AdRevenue Xpress is targeted towards small and mid-sized publishers. It implements Search Box functionality and also features things like a Category Directory as well as the handling of 404 error pages. It can be integrated with your page using a simple on-line wizard.
Conversantmedia (https://www.conversantmedia.com/digital-marketing-products/publishers)
Conversantmedia offers you an impressive 65 percent of what it makes from a click on your website. Payments are done monthly, via PayPal or through checks. The ads can be formatted as you wish, and Fastclick even offers a free support serice for its members and no fees are required to register with the service.
PulsePoint (https://exchange.pulsepoint.com/AccountMgmt/Signup.aspx)
PulsePoint offers the possibility of contextual ads for dynamic pages, meaning ads will change as soon as your page does. It's very easy to use and free to sing up for and offers a transparent payment policy. The ads are fully customizable and real-time reports are available 24/7.
So, as you can see there are many offers for this kind of advertising, and many hybrids based on AdSense like advertising. Also, a lot of services can work together with AdSense to earn you an even greater amount of revenue for your ad space.