Quickly open your favorite folders on OS X?
Select the folder you want in the Finder. While it is selected, press Command+T. 

This will place the selected folder in the sidebar of any Finder window, as well as Open and Save dialog panes. 


Mac OS X keyboard shortcuts (listed under 'Finder keyboard shortcuts')


I should add too that there's a recent folders list available in Finder. With Finder as your current window, click on 'Go' in the menu bar and then 'Recent Folders'. You'll see a list of folders you've been to recently. Selecting one brings the Finder to that folder.