What is Ubuntu Sources List Generator? It is a website where you can generate a sources.list file with a lot of useful repositories.
You probably know that starting with Ubuntu Karmic, you can add a Launchpad PPA using a simple command. Here is a script which will remove the PPA repository, removes the packages you installed from that PPA and install the packages from the official Ubuntu repositories.
Ubuntu Sources List Generator is a website where you can generate a sources.list file with a lot of useful repositories. Besides the usual Ubuntu main, restricted, universe, multiverse, updates and so on you can choose from many others.
An user from the UbuntuForums (blackgr) has made a script that checks your current distribution version (so it works from Hardy to Jaunty and probably Karmic) and them it checks your system for all launchpad sources and will download and install the GPG keys for you.
You can download it from here.
To install it for Ubuntu Intrepid, add the following repository (System > Administration > Software Sources, Third Party Software tab, click "Add"):