My unofficial, as-is, not for profit RPM repositories for EL (RHEL, CentOS, ScientificLinux etc):
These repos may or may not be up to date or behave the way you expect them to; use them at your OWN RISK!
Some of these repos are dependent on EPEL, if you find you're missing a dependency make sure you have the EPEL repo active in your OS.
If you are interested in a particular issue or have a problem feel free to drop me an email at rpm at li.nux.ro.

- Nux Dextop
Summary: A desktop and multimedia oriented RPM repository for EL. It contains a lot of graphical programs such as Ardour, but also text based apps line Cone.
Notes: This repository is made to coexist with Fedora EPEL; it will probably conflict badly with Repoforge/RPMforge and ATrpms and possibly other repos. I try hard not to overwrite Base.
Installation (copy/paste) for EL6: yum -y install epel-release && rpm -Uvh http://li.nux.ro/download/nux/dextop/el6/x86_64/nux-dextop-release-0-2.el6.nux.noarch.rpm
Installation (copy/paste) for EL7: yum -y install epel-release && rpm -Uvh http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-5.el7.nux.noarch.rpm

- Nux Misc
Summary: RPMs that didn't make it in other repos yet.
Notes: These RPMs might not get updated very frequently.
Installation for EL6: Just drop http://li.nux.ro/download/nux/misc/nux-misc.repo in your /etc/yum.repos.d directory. The repo is disabled by default, so you will need to use the --enablerepo=nux-misc yum switch.

My GPG key: http://li.nux.ro/download/nux/RPM-GPG-KEY-nux.ro

If you want to request a package drop me an email at rpm at li.nux.ro or post on the forums.