Try Ubuntu Tweak.
Description of Ubuntu Tweak features on its website:
At present, It is only designed for
Ubuntu GNOME Desktop, and often
follows the newest Ubuntu
* View of Basic System Information(Distribution, Kernel, CPU, Memory, etc.)
* GNOME Session Control
* Auto Start Program Control
* Qucik install common usded applications
* A lot of third-party sources to keep application up-to-date
* Clean unneeded packages or cache to free the disk space
* Show/Hide and Change Splash screen
* Show/Hide desktop icons or Mounted Volumes
* Show/Hide/Rename Computer, Home, Trash icon or Network icon
* Tweak Metacity Window Manager’s Style and Behavior
* Compiz Fusion settings, Screen Edge Settings, Window Effects Settings, Menu Effect Settings
* Set the Shortcuts to let qucikly access your favourite applications
* GNOME Panel Settings
* Nautilus Settings
* Advanced Power Management Settings
* System Security Settings
You should also look into the deborphan and debfoster packages that help you rid yourself of packages that are no longer needed.
Edit: Link to my response to a similar question, one that has examples of how debfoster and deborphan are used in practice.