Because I lost most of my records for last year I'll just list as many theatrical releases (up to 10) that I can remember that were definite contenders.

Good Morning Night, Buongiorno, notte - Marco Bellocchio 2003

The Holy Girl, La Nia santa - Lucrecia Martel 2004

Don't Move, Non ti muovere - Sergio Castellitto 2004

Head On, Gegen die Wand - Fatih Akin 2004

Untold Scandal, Joseon namnyeo sangyeoljisa - Je-yong Lee 2003

Serenity - Joss Whedon 2005

Crash - Paul Haggis 2004

Vital - Shinya Tsukamoto 2004

Howl's Moving Castle, Hauru no ugoku shiro 2004

Ghost in the Shell 2: Innocence, Inosensu: Kkaku kidtai - Mamoru Oshii 2004

Surprisingly easy although there are many other contenders including:

Somersault - Cate Shortland 2004
Turtles Can Fly, Lakposhtha hm parvaz mikonand - Bahman Ghobadi 2004
The Consequences of Love, Le Conseguenze dell'Amore - Paolo Sorrentino 2004
2046 - Wong Kar Wai 2004
The Descent - Neil Marshall 2005
Broken Flowers - Jim Jarmusch 2005

and many more I can't think of right now.

Still unsure as to what I think of Battle in Heaven, need to see it again.

Stand out non-theatrical's include:

3-Iron, Bin Yip - Kim Ki-duk 2004
The Wayward Cloud, Tian bian yi duo yun - Tsai Ming-liang 2005 
and many more.

Cheers Trev.