RPMs on the web:
http://www.rpmfind.net
http://rpm.pbone.net/

Installing:

rpm –ivh (name)

Listing Installed Packages:

rpm –qa | grep (name) to find installed packages

Removing Packages:

rpm –e (name)

Freshen packages:

rpm –F *.rpm

Building RPM from source:
http://wiki.centos.org/HowTos/RebuildSRPM