Well, pick a colour for your current project (I use red). Then mark every step on the path to the file with a red Finder label. Then, when you have to navigate down, all you need to do is find the parent folder and click anything red. It's a lot quicker, and works in open/save dialogs too.
I know there are the Sidebar, the Dock and toolbars, but these are filled up with stuff I always need. I don't want to put extra stuff in there I will only need for a week or so. Labels do the job quite well.

