Ok...lets see....you like serial experiment lain, and paranoia agent? Those are both kinda weird trippy and dream like...except not in a good way...in a dark and creepy way...I LOVE the trippy, in a dark and creepy way genre of anime. If you like that, I would recoment seeing the upcoming anime movie PAPRIKA (paprikamovie.com). Its really trippy and its getting really good reveiws. Its all dreamy like and surealy like Lain and Agent, except even darker then both of them.
If you like really phsycological anime and manga I would recomend Eden (manga), Jin-Roh (anime movie), Urusei Yatsura 2: Buetiful dreamer (anime movie), Ghost in the Shell (manga, anime, and 3 anime movies).
If you like REALLY adult and mature stuff then your safest getting horror manga, because from what I have seen thats the most mature manga you can get (besides hentai). Here is a list of recomendations:
(I warn you these are all really gory)
Uzumaki by Junji Ito
Gyo by Junji Ito
Tomie (they released 2 of 4 volumes a few years ago but those are out of print, they are curently released as part of a 3 volume sereise called museum of terror, volume 1 is about 400 pages and it contains volumes 1 and 2 of tomie, which are both about 200 pages, volume 2 is about 400 pages and it contains volumes 3 and 4 of tomie, which are both about 200 pages, and volume 3 is a colection of short stories by the same author...did you get all that?) by Junji Ito
Parasyte (originaly released by Tokyopop but they droped the sereise because it was to adult for their manley teen audiance, now DelRey is publishing it) by Hitoshi Iwaaki
The ring sereise (ok, this one is complicated, they are all adaptions of the novels by Koji Suzuki and/or the japanese ring films, the manga isnt exactly numberd but here is the order they go in The Ring 1, The Ring 2, Spiral, Birthday, The Ring 0, and they arent even all by the same author, The Ring Volume 1 was drawn by Misao Inagaki and writen by Hiroshi Takahashi, The Ring Volume 2 was drawn by Meimu and writen by Hiroshi Takahashi, Spiral was writen and drawn by Sakura Mizuki, Birthday was writen and drawn by Meimu, The Ring 0 was drawn by Meimu and writen by Hiroshi Takahashi)
Dragon Head by Minetaro Mochizuki
The Kurosagi Corpse Delivery Service by Eiji Otsuka and Housui Yamazaki
The Drifting Classroom by Kazuo Umezu
Ju-On Vidio Side (based on the japanese movie) by Miki Rinno
Ju-On Volume 2 (also based on the movie) by Meimu
Dark Water (based on the book by Koji Suzuki) by Meimu
Hino Horror by Hideshi Hino
(The next few on the list are really perverted)
MPD Psyco Writen by Eiji Otsuka, Drawn by Sho-U Tajima
Koroshiya Ichi (not available in english but if they do release it in the U.S. eventualy, it will probably be translated as Ichi the Killer because thats how they translated the title of the film when they brought it over seas) by Hideo Yamamoto
WARNING: THE FOLOWING IS A GENRE OF HENTAI CALLED EROTIC GROTESQUE, IT IS EXTREMLEY PERVERTED!!!!
mr arashi's amazing freak show (out of print) by Suehiro Maruo
Ultra-Gash Inferno (out of print) by Suehiro Maruo
ANIME ADAPTIONS OF HORROR MANGA:
Midori (adaption of mr arashi's amazing freak show)
Ichi the Killer episode 0 (adaption of Koroshiya Ichi)
If anyone who hasnt seen or read any of the anime or manga I recomended, wants a more detailed description or has any questions then just ask.