Speed shifting is shifting while omitting the clutch. Basically you ram the stick into the next gear without pressing the clutch pedal. Very hard on a gearbox, esp one not designed for it. CART indy cars only use the clutch for 1st gear and downshifts, going up they just ram it into gear. Of couse thouse cars are designed with that in mind, and they use a sequential "motorcycle style" shift pattern.
Zenmervolt
EDIT: Dang it, everyone and his brother beat me to posting. 🙂