I'm in the process of conducting an experiment right now -- advertising my novels on Google Ads.
You see, I received a coupon for $100 of free Google advertising recently. I couldn't use it in my business (needed to be a new google ads account), so I decided to blow it on my novels.
The entire ad/keyword development was a bit too much for me to grasp in the beginning, but the nice people at Google did all the basic work for me. They developed the 35 permutations of the keywords, wrote four ads, and set everything up. All I needed to do was identify a landing page for the ads (I picked Smashwords), and develop a "call to action" (a 40% discount using the code I provided), and I was off to the races.
I set the bid price for each ad was set at $1.00 per click (which is a lot, since my profit per copy is only around $3), and I set a $10 per day limit. Through six days I've had 28,000 views of the ad, 94 clicks to my landing page (at a cost of $72), and...zero sales using the discount code.
But an interesting thing has happened. Could be coincidence. Could be normal momentum. But my sales at normal prices at B&N, Amazon, Smashwords, and Createspace, have all taken a jump upward.
Not exactly a controlled experiment, I'll grant you. There are other promotional efforts going on as well, so I can't isolate the improvement in sales to just this action. But I admit, I'm intriqued.
Now I'm trying a few things with the remaining dollars. Some ads without a discount. Landing pages directly on Amazon, and a lower bid price (at $0.50 per click).
My gut feel right now is that if you have a way to show off all your work on a single landing page, and if you have enough books out there, and if you can get the cost per click price down low enough (yeah, a lot of "ifs") this just might pay off in the short term, and provide longer term benefits as well.
More later if I learn anything else from the experimentation.