I think this would be useful: the ability to select what hidden folders are shown in the folder tree and what are not.
My main use for this would be mucking about with the C:\Documents and Settings directory, where most folders are not shown in the folder tree unless you tick Show hidden folders in options. However, this also shows all the RECYCLER etc. crap that I don't need to see. So, if you could turn the option on only for some folders that would be pretty neat.