A list taken from >>>/dir/ of most 8chans porn boards. Go check them out and make sure to bring something back.
3D
>>>/s/ - Sexy Beautiful Women
2D
>>>/ecchi/ - Ecchi
>>>/h/ - Hentai
>>>/hentaikey4/ - Any Kind of Hentai or Cartoon Porn
Gay-Centered Porn
>>>/cuteboys/ - Boypussy
>>>/him/ - Big Bara Men
>>>/hm/ - Handsome Men
>>>/shota/ - shota
Sexual interests and niches
>>>/ara/ - 2D MILFs & Mature Women
>>>/bbw/ - Big Beautiful Women
>>>/beast/ - Bestiality & Zoophilia Art
>>>/d/ - Hentai/Alternative
>>>/ebon/ - Ebony Girls
>>>/furry/ - Your New Home (Furry)
>>>/futa/ - Futanari/dickgirls
>>>/gif/ - Adult GIF
>>>/hypno/ - Hypnochan
>>>/kemono/ - Kemono Art
>>>/loli/ - Lolicon
>>>/monster/ - Monster Girls
>>>/porngames/ - Porn Games
>>>/rule34/ - Rule 34
>>>/ss/ - Straight Shotacon
>>>/stockings/ - Garterbelts, suspenders & stockings
>>>/tk/ - Tickling
>>>/trap/ - Traps
>>>/ukgirls/ - Girls From The UK
>>>/vore/ - Vore Board
>>>/vp/ - Vidya Gaem Porn
>>>/yellow/ - NSFW Asian Girls
>>>/zoo/ - Zoophilia