There is a lot more of this now than there used to be because every internet slut wants to upload pictures of her cleavage, and porn producers gradually realized there is demand for it. There are also some stereoscopic and 3D porn videos, but they will give you headaches and it's not that worth the trouble yet.
A good Japanese search on Pixiv usually includes "自分視点" (which means "self POV,") or "目線,” but using a variation of "女のPOV" works better on Google/Yahoo. When it doesn't work add a word like "オナニー" (masturbation.)
There's another great Japanese word for looking down at yourself (which I can't remember.)
