Satoshi Kon movies
Cowboy Bebop, obviously
Death Note (I recommended this to a friend and he really likes it. Unfortunately I also mentioned I was watching Geass for lulz so he started watching but he probably forgot about it by now)
Full Metal Panic
It depends on their tastes, though. What you should NOT recommend unless they already have an open mind is anything too obtuse (Lain seems like a bad idea for most people), anything with a ton of inside anime jokes, anything with too much fanservice, anything where the cast are all little girls, etc. Least that's the best way to play it safe.