My old websites had a way to cover up the X-rated parts of a thumbnail image. We called it the Star Tool. In the admin, you could click on an icon next to the thumbnail image and it would bring up another smaller browser window where you could drag and drop one of three sizes of yellow stars to cover up the X-rated parts of a thumbnail, then save the thumbnail. I chose the yellow star symbol as it clearly indicated to the visitor that we took the time to cover up the X-rated parts of the thumbnail, and that once you became a member you could see those parts. So, by using this yellow star function, the entire outside of my website became Safe For Work. I showed this idea to Elise Graves and she suggested that in addition to the yellow star, it would be great if you could select different size blurs instead. See attached sample screen grabs.