Seconding everything here so far. Also:
The falsetto "ah-ah-ah" in Bad Brains' "Sailin' On"
The way the meter actually seems to change in Yo La Tengo's "Here To Fall" (I don't know enough about music to describe this, but it feels like something Philip Glass or Steve Reich would do)
The bongo drums in "Sympathy for the Devil"
The chorus of The Count Five's "Psychotic Reaction"
The guitar riff during the chorus of Buffalo Springfield's "Mr. Soul" (I know it's the same as "Jumpin' Jack Flash," but for some reason I like this one better)
The main riff in Neil Young's "Cinnamon Girl"
The singer from Half Man Half Biscuit singing "I Hate Nerys Hughes"
The bass line in Curtis Mayfield's "Superfly"
The main two samples in Ghostface Killah's "Daytona 500"
The chorus in Ted Leo's version of "Rappaport's Testament"
The opening riff in The Black Keys' "I Got Mine"
That wall of sound thing in The Temptations' "Ball of Confusion"
The chorus of Patti Smith's "Dancing Barefoot"
The way the lo-fi opening guitar comes in with the full band in GbV's "Cut Out Witch" (there's probably a name for this I don't know)
The trial in The Specials "Too Much Too Young," especially when the guy with the Jamaican accent says "take him away" at the end
The opening riff in Black Sabbath's "Sweet Leaf"
Ozzy going "ay-ay-ay" in "Crazy Train"
The main riff in Prince's "When Doves Cry"
Thom Yorke singing "try the best you can/the best you can is good enough" in Radiohead's "Optimistic"
