Planetmirror : Fedora 4, Fedora 3, Fedora 2, Redhat 9
Planetmirror Extras : Fedora 5, Fedora 4, Fedora 3
Repoview (Extras) : Fedora 5, Fedora 4, Fedora 3
Yum search web interface: http://fedoratracker.org/
Fedora Legacy project. Use for obtaining RPMs for older version of RH and FC: http://www.fedoralegacy.org/