Roughly two years ago I created a service where site owners has to include my JS-file to participate. As a result, I now have hundreds of sites with my JS-file included in their theme (mostly sidebars). The question is, can I somehow take advantage of this? I don't want to do something that might be illegal or harm my site's reputation. But maybe something in a grey area which will give me an advantage without harming the users or being easy to spot.