How can I standardize icon size in Finder and across OS X 10.6.8 Snow Leopard?
You can change the default size in the view options panel:



The sizes of icons are also stored in .DS_Store files that override the default setting. You can delete them by running sudo find / -name .DS_Store -delete, but it also resets other display options and removes Spotlight comments. The changes aren't always picked up until you quit and reopen Finder.