Granted, I haven't read every manga there is out there... but among what I have read, I've come across two other characters with the last name Kudo... In Ryo Saenagi's 3 book mini-series "Psychic Power Nanaki", there is Ao Kudo. He is twenty, but looks around fourteen to sixteen as his physical maturing literally stopped with the onset of his abilities - he can see/hear/talk to and exorcise ghosts, he has telepathy and can change one object into another... he usually carries around a stick, which he has on occasion turned into a gun, a bullet proof fan and a huge mat, which he used to catch Nanaki who had fallen from a great height. In that manga, according to the notes, the kanji of his name means either something blue or 'eternal immaturity' - which, due to his abilities, he does seem to be cursed with since he hasn't physically aged. He is a member of an auxiliary group to the police called the "Paranormal Task Force" or (for some reason unstated) the Lock Agency.
In another manga, "Legal Drug" by Clamp, there is Kazahaya Kudo who has the ability of psychometry - only stronger... whenever he touches an object or person, he can read it's history and it's emotions - he lives and works at the Green Pharmacy, whose owner often sends him and his also gifted co-worker out to collect "special objects" that have psychic resonations.
So... even though we all know DC is NOT that kind of manga... does anyone feel that Shinichi was cheated because he doesn't have a special ability? Or can we consider that the way he always seems to happen to be at the right place at the right/wrong (take your pick) time to catch a murderer as his special power? And for the record... I do not think that he is a Shinigami - NEVER!