Agree with raggedjimmi about British coming of age films (European ones usually have that bitter sweet flavour, too) and with Melrose about An Inconvenient Truth.
My own personal favourites, the ones I have been bowled over by, tend to be European. Anyway, here are some which really took my breath away when I first saw them, few rank as "entertainment", but they are formidable films.
Indochine (Catherine Deneuve, absolutely incredible, beautifully shot and wonderful story)
My Life As A Dog (another bitter sweet coming of age movie)
Jesus of Montreal (possibly the most intelligent and thoughtful take on the story of Christ that I have seen on film)
Au Revoir Les Enfants (another haunting coming of age movie, set in a boarding school in war time France)
The Third Man (classy subtle movie from start to finish; great score too, based on a story by Graham Greene)
Lone Star (proof that intelligent, thought-provoking, multi-layered movies can come from the US, a great movie by John Sayles).
For entertainment, I have to cite Quentin Tarantino, (Pulp Fiction and Jackie Brown), and Monty Python (Holy Grail, Life of Brian especially); LOTR is excellent, too. Re Star Trek, I feel that some of the individual episodes of the respective TV series' were actually better than the movies, special effects budgets notwithstanding.
I'm sure that others will occur to me. Cheers