Just some other RPM repositories I like:

CentOS 6 x64: Fedora/Redat; rpm -Uvh http://download.fedora.redhat.com/pub/epel/6/x86_64/epel-release-6-5.noarch.rpm; RPMForge; rpm -Uvh http://apt.sw.be/redhat/el6/en/x86_64/rpmforge/RPMS/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm; RPMFusion Free; rpm -Uvh http://download1.rpmfusion.org/free/el/updates/testing/6/x86_64/rpmfusion-free-release-6-0.1.noarch.rpm; RPMFusion Non Free; rpm -Uvh http://download1.rpmfusion.org/nonfree/el/updates/testing/6/i386/rpmfusion-nonfree-release-6-0.1.noarch.rpm;