In reply to Si dH:
Sobrenada (VS) on Eagle Crag, Grisedale. Pitch 2 has a mildly worrying step across followed by a harder-than-it-looks-from-below chimney.
Square Chimney (S) at Almscliff is a classic of its kind which you have to back and foot (I'll now get told it's an easy layback, or Chris Craggs will say it's a jamming crack or something).
I seem to remember Sail Chimney at Birchen being another back and foot job.
And there's that shiny chimney pitch on Milestone Buttress Direct.