I’m not sure that I saw enough 2006 movies because I had a hard time finding 10 worthies. I suspect better films lurk at the edges — films that would supplant, say, House of Sand,* Brick** or V for Vendetta (though I feel compelled to include one of the better comic-book movies of the Aughts, which was the decade that saw the explosion of a generally underwhelming film genre). But 2006 also gave us what will likely prove to be the decade’s most memorable SF film (Children of Men) as well as Casino Royale, which is not just a superior Bond film but a superior action movie in every category that matters. 2006 also graced us with the untouchable Romanian masterpiece, The Death of Mr. Lazarescu, a film whose significance and layers we’ve only just begun to appreciate (and one of my top 3 or 5 of the entire decade).
As always, movies are listed in alphabetical order, and ‘year’ is determined over at InRO by a movie’s first US release, limited or wide (not festivals or exclusive screenings).
Casino Royale, directed by Martin Campbell (US)
Children of Men, directed by Alfonso Cuarón (UK)
A Cock and Bull Story, directed by Michael Winterbottom (UK)
Crank, directed by Mark Neveldine and Brian Taylor (US)
The Death of Mr. Lazarescu, directed by Cristi Puiu (Romania)
House of Sand, directed by Andrucha Waddington (Brazil)*
L’Enfant, directed by Jean-Pierre and Luc Dardennes (Belgium)
The Proposition, directed by John Hillcoat (Australia)**
Three Times, directed by Hou Hsiao-hsien (Taiwan)
V for Vendetta, directed by James McTeigue (US)
*Not to be confused with Vadim Perelman’s turgid House of Sand and Fog.
**Update: I saw Hillcoat’s The Proposition a few days after this list went live. It has supplanted Johnson’s Brick. It’s also made me very happy; I think it’s the best feature Western since the fat days of Leone/Corbucci.
Also: Ten Favourite Films of 2000; Ten Favourite Films of 2001; Ten Favourite Films of 2002; Ten Favourite Films of 2003; Ten Favourite Films of 2004; Ten Favourite Films of 2005; Ten Favourite Films of 2007; Ten Favourite Films of 2008; Ten Favourite Films of 2009.
(List originally published on In Review Online, on March 11, 2010.)
Roughen 
The Proposition was somewhat ruined for me by the modern Nick Cave soundtrack. Just didn’t quite fit. Glad it made you happy though. (Recently saw Kurosawa’s Tsubaki Sanjûrô on Bluray and it made me very happy).
I would have put Brick, Half Nelson, Pans Labyrinth, The Lives of Others, hell even Miami Vice ahead of Crank.