Ruffles (from top left, clockwise)
Basic Top Down Ruffle
Bell Ruffle
Gathered Eyelet Ruffle
Short Row Vertical Ruffle
Drop Stitch Pleat
Basic Top Down Ruffle
Fluttery Ruffle
Short Row Vertical Ruffle
More ruffly goodness
Barb's Koigu Ruffle from Churchmouse Classics
Ruffle Tutorial from Cotton and Cloud
Ruffles from Interweave's Knitting Daily