I use all five of these utilities daily and they all have had a major impact on my personal productivity.
1. Total Finder – a utility that makes finder much easier to use. It’s killer feature is a tab UI. You no longer need to sift through a group of windows to find the one you need. It’s next big feature is a side by side view which makes moving files a much simpler endeavor.
2. SizeUp – a utility for moving (and sometimes resizing) your open windows. It will dock your windows a predefined locations and will even swap monitors if you are using more than one.
3. Cinch – does some of what SizeUp offers but it is mouse driven. You want to force Safari to go full screen, just drag it to the top of the screen.
4. Alfred App – my preferred app launch (also free). I had been a long time Quick Silver user but I find Alfred to be much more polished and easier to use.