Well there is a world of very good foreign language films out there - much of it far better than the dreck that comes out of the US these days. I used to be far more conversant and frequently went to the cinema to see these but in the last ten years or so this has tailed off. Some recommendations (after looking at my list to jog the grey cells) are:
French
La Cité des Enfants Perdus - you know about this already and the good reviews are valid.
Delicatessen - ditto
Le Fabuleux Destin d'Amelie Poulain - no SF but a delightful film
Jean de Florette and Manon des Sources - again, no SF, but lovely films. The second also has Emmanuelle Beart - of whom you can a lot more (and I mean a lot more in La Belle Noiseuse - which is a very "typical" French film; beautifully filmed but nothing happens - stunning to watch if you have four hours spare, but not sure I would recommend it as such)
Nikita - a Luc Besson film about a female assassin that's been remade, turned into a series, copied...this is the original and fabulous.
Noce Blanche - starring a young Vanessa Paradis as a student who seduces her professor. It's the sort of film that the French do so well. I think it's quite a lovely, gentle film.
Le Pacte des Loups - an action film set (I think) in the French Revolution. Stunning photography and action sequences. Not SF but there is a "beast" (if I remember rightly there's myth about this, based partly on fact, from the Loire)
37.2 le matin - this 'Betty Blue' which I think is a stunning film. For years I actually didn't bother to watch it on video or the odd occasion it turned up on C4 late at night because I'd heard it was basically soft porn. Then one night, I did watch it and realised that it was very much more than that. No SF of course, but what a film. Watch the long version if you can.
If you want crazy car chases and silly humour, then there's the Taxi films.
Italian
La Vita e Bella - you probably know about this wonderful Benigni film
Sedotta e Abbondonata - from 1964 and set in Sicily it shows up the negative consequences of the moral code concerning women at the time. Almost unbelievable to see through today's eyes but an accurate depiction of the way things were at the time (and for some years after...)
Spanish
Abre los Ojos - this is the one that was re-made into Vanilla Sky (fairly faithfully it has to be said) but the original is better
El Espinazo del Diablo (Devil's Backbone) - a great horror from Guillermo del Toro
El Laberinto del Fauno (Pan's Labyrinth) - you probably already know this other del Toro film
Nueve Reinas - a fun, and clever, film about a couple of conmen
El Orfanato (The Orphange) - another great Spanish horror
And if you can handle the plain weirdness, then most of Almodovar's films are worth a look.
There was also a very fine b&w Argentinian film I saw at a festival years ago called La Somnambula in which there is mass memory loss, a machine that can read thoughts and dreams, and a woman that can see into the future. All a bit vague I know but the version I saw had no subtitles and my Spanish is a bit ropey) and it was a bit fantastical. Don't think it's available on dvd though.
Swedish
Lat den Ratte Komma In (Let the Right One In) - a very fine, understated vampire film (I think remade - probably badly)
De Osynlige (The Invisible) - another understated film about an almost dead teenager in limbo, trying to connect with the living world
Tillsammans (Together) - a very funny film set in a commune in the early 70s
Avalon is a weird, but good, Polish film about virtual reality. Last time I searched there were numerous versions available on dvd - so much so that I gave up and so I don't actually own a copy. I do remember it being very good though.
Korea has been producing some great horror/supernatural stuff in recent years. Don't have any on dvd but have seen several at festivals.
And staying in Asia, the classic Chinese supernatural films are worth a look (Ghost Story, Butterfly Murders, etc.) - though I'm not sure they are available on dvd (I used to have bunch of pirated VHS tapes years ago). Many drift into the kung fu genre but that's no bad thing. Speaking of which the 70s stuff such as the Shaw Brothers films are wild - not least because of the dubbing; watching some demented Chinese guy beating the hell out of everyone using praying mantis style kung fu with a thick cockney accent is great fun (Thundering Mantis).
There are many others of course, and some classic French and Italian films especially, but they are on a (probably never to be realised) "to be watched" list.
And I suppose I don't need to mention Solaris?
Finally, you (in particular) might appreciate the Turkish film Dunyayi Kurtaran Adam - clips are on youtube...
