mayor repository ?

I have searched around and I am wondering where the main open source repository's are located? For example I am using eclipse and have the cvs , svn, git , mercurial plugins downloaded and would like to work on some open source projects or at least download them thru eclipse's. I have located and successfully downloaded the apache projects thru eclipse. Their is about 105 different projects in there repository. I am curious where the linux kernel downloads are located? I have downloaded the tar zip source files thru kernel.org site in the past but don't see where the repo location is so I can download it thru eclipse? ( it is obviously cleaner not having to untar and import into my project as opposed to downloading thru git , that is if I can find the repo location). Also curious where the gnome , kde , gcc, grub , x11 , and other gnu open source source code repo's would be at? (meaning I need a repo location for these) Essentially what all this boils down to is is their a repository naming convention or some site that list all the open source repositories because not all sites / projects are clear about where their project is (i.e repo located for it)

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