What I recommended to AgentFakku was to put tags like you do with Youtube videos like forced, pettanko, big boobs. It's hard getting the summaries. All I have is Getchu. Getchu provides the trailers. It's all in Japanese. It shouldn't be hard to navigate.
Tags: Forced, Pettanko, Ecchi, Random, Big Boobs, Swim Suit, Teacher/or Student, Dark Skin, Vanilla, Harem, Demons, Magical Girl
Oh, I found some cool doujins. They're in color which is pretty rare.
The funniest Oreimo doujin was My Younger Sister is by Hyoco Road. It's hilarious. I can't put the cover because it's NSFW. I put this concept drawing for you.