TinkerTool is one of the best tools around for tweaking and changing the preferences on your Mac.
The reason for this is that TinkerTool assumes no prior expert knowledge providing you with a simple interface from which to modify a number of Mac settings such as the Dock, fonts and Safari. Simply check or uncheck the options you wish to keep or not from the different menus. In the Dock for example, you can choose to show system files and animation effects when opening. Just pressing the 'Relaunch' button at the bottom will bring changes into effect. In this latest version, you can also block the Expose feature in the Dock on Snow Leopard.
Many of the features you will find in TinkerTool are however duplicated in free applications such as Onyx but there's no doubt that this app does go a bit deeper and offers more at the end of the day. For example, the uninstaller is useful because it removes associated files for all users on a system whereas free removal tools such as AppDelete only usually remove files for the logged-on user.
Snow Leopard users are at a slight advantage because TinkerTool will recognize what version of Mac you have and show only the preferences that your version supports which are considerably more in Snow Leopard than Leopard for example. Be aware though that changing too many settings can have all sorts of adverse effects on your Mac. Fortunately, TinkerTool includes a 'reset' button on the right of the interface to return to default settings.
The only thing that some existing users may complain about is the fact that no discount is offered for upgrades but for the modest price the developer asks for such a great app, it's a small price pay.
TinkerTool is a powerful and well designed application which will give you far greater control over the look and functionality of OS X.