One little google search shows you an answer to your problem. The answers are free, but do you get to thank the person who put up that website for you?
Every website or blog owner puts in many hours everyday to maintain and add material to their website or blog. And their only secret wish for their effort is that you click one of the advertisements they've put up on their website.
Whether they're entertaining you with reading material, advice or any kind of help, don't they deserve your thank you? Clicking on one advertisement that's relevant to you, would be the best way of applauding their effort as well as giving the advertisers what they want (the primary aim of an advertiser is to get you to refresh the name of their product in your mind :) ).
Could you make that part of your nettiquitte from today onward? :)
