Dragging a file from one folder to another is one of the Great Innovations of Modern Times. It's like the web, or sporks. But sometimes it's a hassle: what if you want to drag a file to a folder...inside another folder? Dum dum dummm...
In comes another Great Innovation of Modern Times: the spring-loaded folder. This allows you to drag a file to another folder through a folder hierarchy. Makes no sense? Give it a try:
Click and hold a file to drag it.
Move the file over a folder and wait a few seconds. The folder opens.
Still holding the file, drag it over another folder. That folder opens.
Repeat as necessary.
Release the file when you're in the folder you want, and all the excess folders close out. You can make the process even quicker by hitting the spacebar key when you're hovering the file over the folder, instead of waiting those few second for the folder to spring-load itself.
[Update:] Two more great tips from readers in the comments (they could do this job for me): From serenity: "Another simple one is that you can change the time it takes for the folder to "spring" in the Finder preferences." Hit Cmd+Comma to open Finder Preferences. And another from aptenergy: "Also, if you drag your item out of a folder that's been spring loaded, it will automatically close." Thanks guys!