As you know, Unmask Parasites is a free independent service. And I hope it will always be free. However, to be able to pay my bills, I placed Google’s contextual ads on this site.
I think, Google AdSense worked well for me (not great though). I didn’t have to search for sponsors – Google picked the most relevant ads from their vast advertizing network for me. The ads are almost guaranteed to be safe (you know, some ad networks fail to detect banners that contain malicious code). And the earnings were enough to pay for the site hosting and domain names (these are the only direct expenses I have).