ok, my suggestion is you should go for adsense, its the best ad program out there ... yahoo is also gud but its limited to US webmasters only!

With adsense, you can also go for chitika, its a also a very nice and reliable prog. Above the main the point is that google adsense is VERY STRICT with its tos, If you try to go agaon their terms and conditions, you 'll be banned forever.

Chitika, you can use it with adsense ... its fully allowed.. Example of chitika+adsense is ours site- [url]www.areyoublogging.com[/url]

And because of any reason you were not accepted with adsense, there are other alternatives also. Some are listed below-
1. Clicksor ([url]www.clicksor.com[/url])
2. Bidvertiser ([url]www.bidvertiser.com[/url])
3. Adbrite
4. Oxado
5. Etology

Best of luck guys