Get rid of those unwanted siblings.

From using windows I know that from time to time you need to do a little housework.. Cleaning!
You want to get rid of those orphaned files, those files that where left behind from an uninstalled program.
In windows you'd be doing this by using one of many programs, that clean the system registry and removes orphaned DLL's.

But how do you do this in linux? and here, I'm thinking Ubuntu.

If you're a normal user you'll hardly run into the problem of orphaned files, because when you remove something you'll tell synaptic/aptitude that it is going to remove the program completely, that means all other programs that depend on this, if you don't, they will be broke afterwards.
But sometimes this approach will tell you that "gdm" (Gnome Display Manager) or some other essential system file are going to be removed as well, and you don't want that to happen..

I have been through a number of installs, to get some other programs to compile. The new Kino 0.8.0 for instance.
I installed quite a lot of dependent libraries, to try and get this thing to compile, and I forgot all about what those libraries where. That's why I was looking for a program to give me a list of orphaned libraries, and I found "deborphan", which will give you a list of programs that you can remove without breaking anything.
And then at the end, or actually you should do this often, run another program called "debfoster", which will keep track of packages you want and the ones that are obsolete. It will ask you a few questions the first time, and then start uninstalling the unwanted programs. Very handy tool.