The gtk orphan package present in the repositories of ubuntu can be conveniently used to clean up your system. It allows you to graphically select and remove packages that are no longer used.
On Ubuntu 9.10.Install gtkorphan as below.
$sudo apt-get install gtkorphan
A new menu entry will show up as System-Administration->Remove Orphaned packages.
Select the orphaned package you want to remove and click ok.