Alternatives to Google AdsenseGoogle Adsense is probably the largest group of advertising publishers online and as a result can pay very well if you have a website with quality traffic in a profitable niche.
Unfortunately, sometimes for one reason or another you are unable to get or use an Adsense account. The reasons you can't use Google Adsense are plenty, sometimes you live in a Country where Adsense is banned, or perhaps you've been banned for doing something in the past and need some sort of Google Adsense alternative to help pay the bills.
Regardless, of why you can't use Adsense, it is not the end of the world, there are many great Google Adsense alternatives out there that will help you make some extra money with your web site.
List of Google Adsense Alternatives:
Yahoo Publisher Network - http://publisher.yahoo.com
YPN is probably the best Google Adsense Alternative, however the biggest issue is that the Yahoo Publisher network has even more strict rules to get in than Google Adsense. So if you want to use Yahoo as an alternative, you need to make sure your site is super clean, and you fit all the requirements set forth in their TOS.
Chitika - http://www.chitika.com
Chitika has a number of advertising products that website owners can publish to generate revenue. Chitika Premium is a great product that only shows ads if a user comes in through a search query, thus not bothering your return visitors with ads. Chitika uses the search term to create relevant ads and if for some reason you still are able to use an Adsense account, they are allowed to be placed on the same page as Google Adsense without violating the Terms of Service.
AdBrite - http://www.adbrite.com
Adbrite is an interesting ad network. What is different about Adbrite in comparison to other networks, is they have their standard Run of Network ads, but they also allow advertisers to buy ads directly through your website in one of your ad blocks. You have the ability to set the rate for these direct purchases to ensure you get the value you want for your ad real estate.
In Text Google Adsense AlternativesWhile standard ad blocks are a great traditional way to make money, sometimes you need to spice things up a bit and think out of the box. There are a few companies now that offer contextual advertising within your existing content. Basically these companies have a little script that will spider your content when a user loads it, and underline specific relevant words that then become ads if a user mouses over them. These ads can be very lucrative and can make you some very good money when combined with the the other Adsense Alternatives above.
Kontera - http://www.kontera.com
Kontera is a great company who I've used numerous times before and pays like clock work every month. The reps are very friendly and tend to email you to check up on you and see if there is any way they can help improve your revenue. If you make checks consistently they will even negotiate the revenue share percentage.
Infolinks - http://www.infolinks.com
For somebody who needs an alternative to Kontera there is also Infolinks. The debate on which one is better is kind of like the age old argument weather Google Adsense or Yahoo Publishers Network was better. You can be the judge.
Chitika Select - http://www.chitika.com
Chitika Select is the newest player in the in text game, and while they are still very new I have heard good things. I don't have much experience, so if you have tried them out and have something good or bad to say, please post it as a comment!