As the others have said, comb picks. They aren't exactly renowned for their reliability but it can be done; most lock manufacturers take measures to prevent this but it can work on certain (usually low end) locks. Although even with locks that can be combed, the commercially available picks really suck. This type of attack is fended off by simple warding in the keyway most times... not to mention most padlocks that can be combed are almost guaranteed to be susceptible to other forms of bypass anyway, provided they don't use ball bearings.
As for cylinders, I've seen it done but not with the commercial picks that you can just buy off the interwebs. Not something I'd hold high hopes for, but it's neat if and when it works.
