Lupin III is awesome. Better to get the newer movies like Alcatraz and Castle of Cagliostro. The original series is only good if you can put up with the 70s music and animation (i can't). Trigun, Cowboy Bebop, Initial D, FLCL (too short) and Golden Boy (also too short) are probably the best ones i've seen. I've seen heaps and just cant remember them all but if you want something that will really screw with your head then you should watch Serial Experiments Lain: watched the whole series 3 times and still hard to understand it properly.