Dave Caolo showed you how to take control of the Finder's sidebar a couple weeks back. Today, I wanted to shed the same light on the Finder's toolbar, as you can customize it and add some tools not found in a default Mac OS X installation.
The first thing I like to do is add 'other' kinds of folders (and files) up there, such as my Library, that I don't necessarily want in my sidebar. To do this, you can drag a file or folder up next to the buttons in the Finder, and wait a second - you won't receive instantaneous feedback like you do when adding something to the sidebar. After a second or so, the Finder's search box will move over farther to the right (like when you add something to the Dock), signifying that you can now add that item to the toolbar.
You can also add a few more tools to the Finder toolbar by right-clicking on it (just like many other application windows) and choosing "Customize Toolbar." You will be presented with a whole set of handy buttons and actions you can drag and drop to add such as eject, get info, connect to server, burn and more. Even though we covered how to get a file or folder's path by command-clicking on a window's title bar icon, I also like to add the Path button to the Finder's toolbar with this trick for one more level of convenience.
Since I'm willing to bet that I haven't covered all the Finder toolbar tricks, feel free to share yours in the comments.