I agree that Full Metal Alchemist is good of course I haven't seen the entire anime series yet and am only on volume 2 of the DVD's.
But naturally I have to say that the must see anime(s) ever are Sister Princess and Hanokyo Maid Team.
Both are very simmular but very much different. Sister princess is about the highschool life of one Wazoo ?? and his 13 younger sisters that he never knew he had all living on this one island with only one school and it seems that the sisters are in love with him but if it weren't for them being siblings incest would abound.
The second one is about an 8th grader named Taro Hanokyo who when the story begins is saying goodby to his mother's grave as he leaves to live with his grandfather whom he has never once met not even on the day he was born. Hormones seem to slightly abound in this three volume 12 episode series with a third year middle schooler as head of his family a grandfather that disappears before he shows up, a mantion bigger then most countries and a maid team the likes of which all love him very much and will do anything for him. more then 1000 maids it seems form security to three who's job it is to warm is bed up ie sleep with him and many many more antics. don't know how many other episodes will apear or if they'll have a movie I only have the first volume.