Good Bye Lenin!. It's the only German comedy that actually made my non-German-speaking friends laugh, and it's... good. Definitely not a mindless comedy. Two other German films I really like would be The Lives of Others and The Counterfeiters.
Recently watched The Pianist, it was good. Been out a long time though so I don't really know why I hadn't seen it before.
Katyn (Polish film) is sad but a good one.
Gentlemen of Luck and The Diamond Arm are both Soviet comedies, but some of my favorites. The latter at least can be watched for free with English subtitles on Mosfilm's YouTube channel. Admiral is a newer Russian film that most people I've watched it with have enjoyed.
?Dark Blue World? is also pretty good; it's in Czech.
I've started watching some Russian miniseries based on some of the classics of Russian literature. Most of what I've seen of them I've been relatively impressed with, so I'll probably try to watch some more of those.
Plenty of others that I like too; just can't think of many more at the moment. I watched ?The Footnote on the plane back from Ukraine; it was in Hebrew and it's hard to follow subtitles while the passenger next to you is talking, but the idea of the movie was interesting anyway. Not exactly an all-time favorite though, just watched it because I like watching odd foreign films and I had seven hours to kill.