The late Gary Driscoll on the first Blackmore's Rainbow LP: "Still I'm Sad", "Black Sheep of the Family" are the 2 tracks that come to mind... I like the way he layered the cowbell into the rhythm (a "ride cowbell", so to speak). Driscoll was also in Ronnie Dio's pre-Rainbow band, Elf, and I have heard a few recordings by them with his distinctive cowbell in the mix.
On a related note: do any drummers or percussionists ever use a cowbell with a clapper inside ? Or is that type of bell strictly for cows ?