@Mr_NutterButter boorus aren't just for hentai. They're image sites where you can search for images based on tags. Rule34 is an image booru, for instance. A lot of people just search for "x character hentai" though and end up on these websites ridden with ads and probably viruses.

Gelbooru is the big one. It's pretty nice. Has a good mix of hentai and normal stuff in it. E621 is for furry shit, and they have a sfw version of it called I think e926 or something.