It seems I've been a lot into Otaku/Hikikomori styled animes lately. I've been very interested in the typical Japanese lifestyle, especially people who have problems with being sociable, probably because I can relate to that.

So lately I've been addicted to the anime "Welcome to the N.H.K" and the novel "Train Man".

I could name a few other examples but I think these are the best.

Can anyone recommend me other animes/books/mangas that deal with this kind of topic, i.e. Otaku/hikikomori life (and maybe even a little bit of romance)and the like?

Genshiken, if you haven't seen it.
Otaku no Video, if you can stand the age.
Nogizaka Haruka no Himitsu, if you can stomach a (mediocre?) moe spin on the idea.
Comic Party, which I haven't seen and can't really recommend.
Doujin Work, which is less honest otaku life and more comedy.

Other than that, I'm coming up blank. It's a shame; I like that genre too.

Sayonara Zetsubou Sensei: Suicidal Teacher in Despair with a classroom full of weirdo girls: stalker,hikkikimori,illegal immigrant,foreigner,perfectionist, Mute offensive girl that only sends..offensive emails rofl,optimistic girl etc etc

"mure mure mure" it had to be said.

I know its not an anime, manga, or a book... But if you got a PS2 try getting into the Persona series. I haven't played it personally, but from what I've seen its awesome