When you're working on a bunch of related documents at once, you might want to jump quickly to their folder in the Finder. Normally, of course, you'd switch to the Finder and navigate through your hard drive to get to the correct folder. Or perhaps, if you're a power user, you've already put the folder in the Finder's Sidebar for easy access. Either way, though, you have to switch to the Finder and open a new window, which is a massive waste of time.
Why go through all those steps when you can get AppleScript to do it for you? Using AppleScript, you can save a folder-opening script as an application (Section 2.2.2) and place the script on the Dock for easy access. From then on, all you'll need to do is click the script's icon in the Dock, and a Finder window pops open and takes you right to the folder you want.
"But wait," you say, "I could just put the folder's icon on the Dock, no script required." You are, of course, correct—and your method is what most people use for accessing commonly used folders. The trouble is, when you click a folder's icon on the Dock, you never know where the folder's window will open onscreen, or whether it'll be in List, Column, or Icon view. Plus, a folder icon on the Dock can open only one specific folder, whereas a script can open multiple folders at once—like your Music and Pictures folders—as shown the following example:
tell application "Finder" activate open the folder "Users:yourUsername:Music" open the folder "Users:yourUsername:Pictures" ...