Burn, Stargazer, Gates of Babylon, Black Night are my favourites of Blackmore's. He really knew how to base a good song around a good riff.
Others:
Megadave: Symphony of Destruction, Hangar 18, She-Wolf (verse), Reckoning Day
Jon Schaffer: Setian Massacre, I Walk Alone, Infiltrate/Assimilate (Tim, if you wrote that riff, credits go to you), Dracula, Phantom Opera Ghost, Frankenstein. Heck, when he's not singing Star Spangled Banner to European journalists, he's galloping out the best riffs in metal, by the bulk.
John Petrucci: About to Crash Reprise. THAT is one rockin' riff.