This is what I have done and want to know what do you think and how I can improve it. I am not making much money now and I don't expect to make much in the future ($100/month is a very good month). This is mostly for fun and challenge. I have signed up for as many good (4 or 5 Network Earning) advertisers. In PHP, I gave a weight of 10 to each. Then randomly select 3 advertisers from this list based on their weights (at this time all have the same chance) and place a banner (120X60 at this time) on my site. Every 2 weeks I would check the stat and modify the weight based on the CTR and CPM. To calculate the new weight, I am planning to use the following calculation: 10 + 100*CTR + 10*CPM So if an ad has a CTR of 0.24% and a CPM of $5, the new weight would be 10 + 100*.24 + 10*5 = 84 If an ad does not have any click, I reduce its weight by 4. So if an ad does not any click, it will be removed in 6 weeks. During the 2 weeks maintenance, I may add more ads with the weight of 10. What do you think?