Underrated Movies

I'm sure you've come in contact with several. Basically those movies that were big upon their release but have faded away, got lost in the mix or simply just didn't do well despite the critics liking them.

I've seen (and reviewed) several of these underrated gems, most of which I can recommend to others (Moon, Wonder Boys). Sometimes it surprises me for why they don't do well, especially, like as I mentioned above, when critics love them.

So I ask you this: what are some underrated movies you recommend highly?