Search flickr, go into advanced search, click “Showing Creative Commons-licensed content for commercial use”, and you can use the image for what ever you want. including blog posts. enjoy!
Technique: Doing a search on a keyword, can help you visualize your search. Use flicker or just google images to find a “visualization” of your writing topic. A few pictures can really help focus your ideas about the certain experience you are looking at. I never really encourage only keywords as your marketing strategy. I think on the keyword level, there is a basic idea that provides tremendous brainstorming ability. But overall marketing should be about presenting an idea or concept that encompasses what you believe to other people who believe in the same ideas. Then introduce a product that you use, why you gain value from it, how to use it, and how to share it. Immediately, people understand its power, and why you use it. Why they should use it. And the value of it.