i thought these are great intros along with the song
in no particular order -- im trying to remember some more - i gues if i remember those of the top of my head then i gues i consider them pretty memorable - im not counting just the song or the visuals im counting both together - example fushigi yugi has a good song but i think the song is better than the visuals
edit: just noticed the title says song = singing
im not sure if hakenden has singing i dont remember any but none the less i still think its one of the greatest intros
Witch Hunter Robin and Hellsing Definetly. I also really love sakura saku from love hina, trust and justice from vandread (and himegoto the end themse). Change the world from inu yasha. Also the title theme's to Ah My Goddess, and Hand Maid May.