Originally posted by Arpe
Pixsy - Find and Fight Image Theft is a service you can sign up for for free, and on a free plan, can have it monitor up to 500 images. If you're a prolific online poster, that's not much, bit it's enough get get some sort of picture of how much people are using your images.
It's up to you whether you take action or not, and what sort of action you take.
Depending on whether the site is commercial or not will have some impact on my thinking. If they're making money through the help of my photos, I want to too. If they're a non-profit, I'll take it on a case by case basis. 'Non-profits' are just that - they aren't allowed to operate for profit, but some still have substantial budgets, and things like websites often get covered by grants or donations, and they'll acknowledge their sponsors. If they've used me as an 'involuntary sponsor' without recognition, when they've acknowledged other sponsors, I'm liable to get grumpy.
If I'm asked for permission in advance, I'm generally happy to let non-profits use my images.