There are three updated yum repositories for RHEL/ CentOS. Remi and Webtatic repository are my favorites. Follow below steps to install some other repositories into yum.repos.d.
Install epel Repository
64 Bit OS
[root@myserver tmp]# wget http://download.fedora.redhat.com/pub/epel/5/x86_64/
epel-release-5-4.noarch.rpm32 Bit OS
[root@myserver tmp]# wget http://download.fedora.redhat.com/pub/epel/5/i386/
epel-release-5-4.noarch.rpm[root@myserver tmp]# rpm --import http://download.fedora.redhat.com/pub/epel/
RPM-GPG-KEY-EPEL
[root@myserver tmp]# rpm -K epel-release-5-4.noarch.rpm
epel-release-5-4.noarch.rpm: (sha1) dsa sha1 md5 gpg OK
[root@myserver tmp]# rpm -ivh epel-release-5-4.noarch.rpm
Preparing... ########################################### [100%]
1:epel-release ########################################### [100%]Install Remi Repository
[root@myserver tmp]# wget http://rpms.famillecollet.com/enterprise/
remi-release-5.rpm
[root@myserver tmp]# rpm -Uvh remi-release-5.rpm
warning: remi-release-5.rpm: Header V4 DSA signature: NOKEY, key ID 00f97f56
Preparing... ########################################### [100%]
1:remi-release ########################################### [100%]Install Webtatic Repository
64 Bit OS
[root@myserver tmp]# wget http://repo.webtatic.com/yum/centos/5/x86_64/
webtatic-release-5-2.noarch.rpm32 Bit OS
[root@myserver tmp]# wget http://repo.webtatic.com/yum/centos/5/i386/
webtatic-release-5-2.noarch.rpm[root@myserver tmp]# rpm --import http://repo.webtatic.com/yum/RPM-GPG-KEY-webtatic-andy
[root@myserver tmp]# rpm -K webtatic-release-5-2.noarch.rpm
webtatic-release-5-2.noarch.rpm: (sha1) dsa sha1 md5 gpg OK
[root@myserver tmp]# rpm -Uvh webtatic-release-5-2.noarch.rpm
Preparing... ########################################### [100%]
1:webtatic-release ########################################### [100%]How To use these repositories
yum –enablerepo=epel install [rpm package]
yum –enablerepo=remi install [rpm package]
yum –enablerepo=webtatic install [rpm package]