There are hundereds of Ad netwoks which help you to make money online. Here, i have listed only few good networks which i used and provide on time payment.

1. Google Adsense
This is where most of the “Make money online” bloggers / webmasters start their dream. It’s worth to start your “Make money online” journey from here. You can display image and/or text ads in your blog using this Ad Network. See my right sidebar in my blog for the demo. HIGHLY RECOMMENDED

Signup for Google Adsense.

2. Adbrite

Adbrite provides the same service as Google Adsense minus the content relevant ads. Unlike Google Adsense here advertisers apply to advertise their ads in your website. It’s your wish which ad to select and which to leave.
PS: There is also an auto approve option.

Sign up for Text Link Ads

3. Paypal

Pay online
* Speed through checkout whenever you shop online.
* Pay without revealing your credit card information.
* Send money to your friends and family.

Sell online
* Accept credit cards quickly and easily.
* Lift your sales. Add PayPal to attract more customers.
* Get tools to make eBay sales simple.

You can also refer your friends to this service and make money.

Signup for a free Account here

4. Read my posting “Make money with your Orkut profile in Just 10 minutes” to learn how to make money from your social profiles.