Google AdWords Quality Score
Google's AdWords program has included a quality rating for each keyword and ad combination for quite some time now. What's relatively new is that they've made this score publicly visible to advertisers. Of course, the specifics for how the score is calculated is still a secret, but at least you can see now whether your score is poor, OK, or great. Anything other than great, of course, should be addressed.
The quality score is hidden by default so you have to turn it on via the customize columns drop-down. Once turned on, every keyword in the ad group will include beside it a rating. This rating isn't, as far as I can tell, calculated in real time so any changes you make in an effort to influence the rating won't have an effect right away. Still, it is worth your time to make an effort to improve your score since doing do can reduce your cost-per-click (CPC).
When the quality score was first made public, I was quite interested in seeing my own ratings. On the one hand I hoped that everything received the great rating, but on the other hand I wanted to have a lower rating since that would mean I had room to improve and reduce my click costs. In reality, I had a great rating for 80% of my keywords with the remaining 20% rated as OK.
The first and easiest approach to addressing quality issues is to use the peel-and-stick tactic that I've used for a long time, but the name for which I first heard of from Perry Marshall. This tactic simply involves peeling one or more keywords from an ad group and sticking them in to a new ad group. The idea is that with this new ad group you can write a more targeted ad perhaps with the keywords in the ad title. Sometimes this is all it'll take to improve Google's measure of quality.