fchan

Of course the site is http://www.pixiv.net

Here is a video to help you register:
http://www.youtube.com/watch?v=yN3brutcykA

Here are some helpful keywords. Hopefully fchan doesn't mangle the Kanji. If you want a keyword for something else and can't guess it then you can ask here.

Also, one easy thing to do to be gender specific is to add the character for either Male or Female to the end of your non-gendered word.

Male: 男

Female: 娘

Penis: ちんこ

Breasts: 巨乳

Boobs: おっぱい (Vulgar)

Anus: 肛門

Hermaphrodite: ふたなり

Shemales: シーメール

Kemono (Furry): ケモノ

Animal People: 獣人 (Sometimes used instead of Kemono and vice versa.

Monster:  モンスター

Monster Girl: モンスター娘

Muscle (Generic): 筋肉

Muscle (Female): 筋肉娘

Muscle (Male): 筋肉男

Muscle Abs: 腹筋

Giantess: 巨大娘

Amazons / Warrior Women: 女戦士

Warrior Men: 男主人公

Gay: ゲイ

Homo (Male Gay): ホモ

Sex: フェラ

Intercourse (straight sex): 性交

Anal: アナル

Reverse Anal (Males receiving anal): 逆アナル

Rape: 強姦

Reverse Rape (Males being raped): 逆レイプ

Fetish: フェチ

Perversion: 倒錯

LGBT Artists: LGBT アーティスト

Bukakake (Ejaculation): ぶっかけ

Slime: スライム

Pokemon: ポケットモンスター (Pocket Monster) or ポケモン (Pokemon)

R-18: Adult

R-18g (Adult / gross)

I cant see it; just some blocky things.