These errors are pretty much harmless (though they probably slow down "apt-get update" a bit) but if you want to get rid of them anyway, you must disable the PPAs that cause the 404 errors via Software Sources. If you want an easier, automated way to disable the PPAs that cause these errors, give "fix404" a try.

PPASearch is a simple tool you can use to search Launchpad for PPAs (Personal Package Archive) which provide a package/application you're looking for and also add the PPA - all from the command line.

This is something I've been looking for a long time - amazing idea! However, there is one thing missing from PPASearch (I'm not sure if it can be implemented though): listing the version in each PPA for the application you've searched for.

GetDeb is a website which comes with a repository for easily installing lots of Ubuntu applications which are not available in the official Ubuntu repositories (mostly updates). PlayDeb is the same as GetDeb, but for games.

Both the GetDeb.net and PlayDeb.net websites are currently down but if you want to use the repositories, there is a mirror you can use instead of the original GetDeb / PlayDeb repository.

Ubuntu Sources List Generator is now available for Ubuntu 10.04 Lucid Lynx.

What is Ubuntu Sources List Generator? It 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 such as repositories for: AWN, Ailurus, Banshee, Cairo Dock, Chromium, Deluge, GetDeb, Ubuntu Mozilla Daily, OpenShot, Skype, Pidgin, PlayDeb, PlayOnLinux, SMPlayer, Terminator, Ubuntu Tweak, XBMC and many more.

You probably know that starting with Ubuntu Karmic, you can add a Launchpad PPA using a simple command:

sudo add-apt-repository ppa:THE_PPA

Ubuntu Tweak 0.4.9 has been released, a great application for tweaking settings in Ubuntu (Hardy, Intrepid, Jaunty or the latest development Karmic). From this version, Ubuntu Tweak has different package for i386 and amd64 and works for Karmic too.

-Separated Source List: you will have a more manageable way with Third Party Sources. By default, Ubuntu Tweak will save the third party sources into its own file under /etc/apt/sources.list.d/

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. All you have to do is select your Ubuntu version on top of the page, and you will be able to select from the following repositories, under "3rd Parties Repos": Amarok 2, AWN, Banshee, 9+1 great Ubuntu complete themes (including gdm, emerald and awn themes), Cairo Dock, Chromium, Conky, Deluge, Gnome-Colors, Gnome DO, Google Linux Software Repositories, Medibuntu, OpenOffice.org, Mozilla Daily Build Team (Firefox 3.5), both Opera stable and Opera beta, Skype, VLC, Wine, XBMC Media Center and many others.

Debian users: there is also a Debian version of the Sources List Generator, so you may want to check it out.

Once you have selected all the repositories you want, click the "Generate" button and you will then be able to copy the repositories into your sources.list file:

gksu gedit /etc/apt/sources.list

For adding GPG keys of new repos, see instruction (if available) in the generated sources.list itself. To add the GPG keys for all the repositories at once, see this script which automates the key importing process.

If you remember the great 9 complete Ubuntu themes that also had a repository to install them (and for updates) and liked them, you may want to know that the author (zgegblog) released yet another great theme called Showtime.

The theme includes:

* A background theme
* GDM Theme
* GTK Theme
* Metacity Theme
* Emerald Theme
* An icon pack

Before installing, you may also want to take a look at some Showtime theme screenshots:

sudo apt-get install showtime-theme