Sound and Vision - David Bowie, it takes half the song to get to the lyrics, by which you've been introduced to pretty much the whole gamut of heartbreaking emotions of the song...
Our Prayer/Gee (which is the first track of Smile, so it's the intro!) - Brian Wilson... sooo beautiful, beach boy harmonies at their best
Search and Destroy - Iggy & The Stooges, like "I'm a street walking cheetah with a heart full of napalm" couldn't be great...
Tomorrow Never Knows - The Beatles... once you hear those first few seconds you know nothing will be the same again... timeless.
Baba O'Riley - The Who... enough said, the intro to bury all other intros... ok, yeah I know... you know what I mean...
Like a Rolling Stone - Bob Dylan... I can't bother myself to explain.
I Have Been in You - Frank Zappa... it's just such a great doo wopish intro to a song that's about the physical aspect of sex (and a prominent song in Wong Kar-Wai's Happy Together movie about two chinese gay guys in Buenos Aires)... just to keep up the pun, I have been in and out of Zappa through the years...
Everybody's Talkin' - Harry Nilsson... Although I prefer Fred Neil's original version, the intro of Nilsson's version keeps buzzin in one's head... maybe because it's used all throughout the song (and the Midnight Cowboy film)?
and the curveball...
Farmer in The City - Scott Walker... which you can find in his 1995 Tilt album... there is no intro like this anywhere (first song in the album too), except maybe in avant garde opera (of which I know nil)... it gives me the chills still, after 13 years...