When switching to a side-positioned Dock, one thing I really missed was being able to have my Documents and Downloads stacks in “Fan” mode. Fan mode allows you to view a list of files but also has dragging capability.
Thanks to Onyx, I found a nice hidden preference for Dock which allows you to use a new list which seems to draw inspiration from iOS and also restores dragging ability.
To enable the “new” list mode style open Terminal.app and enter the following commands:
$ defaults write com.apple.dock "use-new-list-stack" -bool true
$ killall Dock
Your dock should restart and any stack using the list mode will be in the new style.