Take the File > Add to Sidebar (command-T) feature that I forgot all about until listening to Thursday's MacBreak Tech episode. The beauty of the Finder's sidebar is that you can drag anything you want into it, including folders (including those from networked volumes like an iDisk), files and even applications. Your customized sidebar is then available in every Open and Save dialog throughout Mac OS X, making it a great spot to quickly place and remove projects you're working on, apps you need for a short time and important folders in which you need to often save or retrieve things.
The sidebar gets even cooler, however, if you can wiggle that keyboard shortcut to your workflow. Got a file you need to remember later today? Cmd-T. A pictures folder you use for blogging that's buried deep in your Home folder? Cmd-T. A bunch of applications you're testing out for business or pleasure? Boom - that shortcut makes it easy to turn your Finder sidebar into a pseudo-cork board for all the stuff flying up and down your todo list, since all you have to do to remove an item is click and drag it off the Finder window to get that satisfying 'poof.'
Combine this trick with our Mac 101 tip for adding your own items to the Finder's toolbar and you can put together one mean, lean window that can let you browse your files faster than ever before.