In case none of the above works for you:
I've done quite a few Postgres installations, but was flummoxed today on a RedHat 6.5 system (installing Postgres 9.3). My typical hba.conf configuration that Aron shows above didn't work. It turned out that my system was using IPV6, and ignoring the IPV4 configuration. Adding the line:
host all all ::1/128 password
allowed me to login successfully.