If you feel that there are too many things on your Finder sidebar, you can hide some of the rarely used items. It's very easy to hide the items; You only need to drag-drop it out of sidebar.
However, if someday you feel that you will need the item again, you can:
But up to now, I still can't find the way to hide the sidebar while keeping the toolbar shown, like in Tiger (Mac OS X 10.4).
Some articles taken from our resource base, tightly related to current article, to empower you with more knowledge on tweaking the most out of your Mac.