there are no clsids for icons. although there are the clsids for special folders like control panel, printers, modems, drives, etc.
what i infer from what you said might be this: you want the open / closed folder icons to be customized. am i right? so here you go. fire up reshack and load shell32.
dll. on the left pane you'd find many words like avi, bitmap, icon, cursor &c. navigate to icon group. expand the group. you'll find many numbers in increasing order.
your exercise just began. try navigating each icon group number. you'll be surprised there are a whole lot of icons to customize. rest of what i meant can be had from
here.
as for my music / my pictures / my videos, fire up regedit and expand HKEY_CLASSES_ROOT>CLSID. you'll be amazed there're a whole lot of clsids for anything you need customized.
ciao!