In reply to cb_6:
about 30% of my training is leg stuff and i find no increase in mass or weight. it simply depends how you train. for serious leg capacity you need to train several aspects - legs are complicated structures and just raw lift power or light running is only part of the picture.
make part of it whatever squat turns you on (tho wouldnt zerchers be harder to position than f-squats?), but do narrow squats and follow thru into calf raises too, as well as lunges.
if you cant add weight to the bar add it to yourself with a pack or romanian bag over your shoulders.
chains are good for working balance and thrust.
single leg DLs are good, as are plyometric jumps (box and depth) and assisted pistols as mentioned. lateral jumps over a barrier are good stuff.
the finest leg ex i cann think of tho is running/walking with a weighted pack. tho many hate it, the best results i see are from this and if trained properly need not mean injury (plenty of soldiers, construction workers and and firemen do it). keeps mass down when trained with other stuff, including regular running (even better, on soft sand).