What are some nice algorithms/techniques for optimizing and predicting Click Through Rates (CTR)? Definition of Click Through Rates:


  CTR is the number of clicks that your ad receives divided by the
  number of times your ad is shown expressed as a percentage (clicks ÷
  impressions = CTR).
Logistic regression is very common and efficient.

This will provide you with a probability of click for a given impression. You will likely need additional information for optimization, like keywords or A/B testing.