In no particular order:
Bladerunner
The Life of Brian(hilarious: 'nuff said)
Donnie Darko(that paradox stuff is great, takes a few watches before you get the idea that the whole movie can't happen: or can it: the old lady

)
Ice Cold in Alex(great buddy movie, and a demonstration of how predudice can be overcome by adversity)
Cassablanca(the dialogue is the sharpest and most observant I've seen in a long while)
The African Queen(just twee but damn inspiring)
Lord of the Rings(all three, special effects, keeping it close to Tolkein: a buffs film/s)
The Seven Samurai(superb and brilliantly funny)
The Sting(great twist)
The Raiders of the Lost Ark(action movie at it's finest, and brilliantly dry humour)
Damn I have ten more too in no particular order, too many great movies, can we extend this to 20?
Brazil( now that film is clever and funny, if ever you meat a beureaucrat just think of this film, and his small mindedness will make you laugh)
Monty Python and the Holy grail
Underworld(great plot:underated IMO)
Apocalypse now(for the Carmina Burana thing if nothing else and the quote: I love the smell of napalm in the morning)
GoldenEye(how to do Bond well, hats off to Sean the best Bond ever, but for sheer fun this movie rates: pity they didn't follow it up with a great movie or two)
Blade(all of them if I could)
The Good the Bad and the Ugly( the quintessentail country and western)
Gattica(sublime: great way of showing it's not about what you got, it's what you do with it that counts)
Pleasentville( yes cheezy in parts but a great little tear jerker)
The Excorcist( this is how you do horror: not matched until The Ring: Japanese or other wise) Blair Witch eat your heart out.
Can I do top 30 in no particular order
Fight club(possibly the sharpest dialogue and cleverist observation of anarchist behaviour you'll see)
Henry IV(Kenneth Branagh version: the other one is good but too hammy: it made me want to go over to France and fight them: Orleans and st crispins day speech: some propoganda here but damn it a great piece of story telling: once more unto the breach dear friends or close the wall up with our English dead)
Ahhh.. no I could go on all night
