Watch the Stairway: Ex. 3b online guitar lesson by Andy Aledort from Kings of Rock & Roll Vol. 7: Jimmy Page

I begin this "Stairway"-type solo with a fast pull-off riff based on A minor pentatonic: after fretting a high C (second string/13th fret), I pick a D two frets higher, bend up one whole step and release, pull-off back to C and then finish the phrase on A, third string/14th fret; the pattern is then repeated a number of times. Cycling a lick in this way is an effective way to build tension in a solo.
This solo excerpt ends with a fast, repeated pull-off riff up in 17thy position; this riff has been used liberally by all of the rock guitar greats, including Jimi Hendrix, Johnny Winter and Duane Allman.