Images are a very important part of any product, article or website. Here are a few free resources for high-quality images: sxc.hu, Wikimedia Commons, Public Domain Photos, FreeImages.co.uk, FreeFoto, Flickr CC, Public Domain Pictures, USDA Gallery.
You can also use a payable resource, where professional photographs and designers offer their works. One of the best is iStockphoto.
Google has a series of search modifiers that allow you to perform very specific searches, these include [inanchor], [intext], [intitle], and [inurl]. In addition you can also add the word [all] in front of each term to include all of the words in the phrase. These modifiers can also be combined with the [”] , [-], and logical operators and be used to create complex queries.
Useful for researching your competitors to see what kind of websites they own.
For correct referrals from banners, emails or other non-trackable sources.