Leaving out the more, um, responsible suggestions which includes work from Tarkovsky, Buñuel, Dreyer, Bergman, Bresson, Kurosawa, Mizoguchi, Antonioni, Vigo and so on,
these are the movies I've enjoyed the most/had the most impact on me in the past 10/20 years or so.
Ahhh, guilty pleasures. And a dark, dark subconscious, apparently.
Regarding French movies, if you don't mind a few core values shocked, I would say C'est arrivé près de chez vous. I think it is sold in the US as "Man bites dog". And if you want something really different, try Delicatessen by Jeunet and Caro.