From LQWiki

To configure what services are started in the different runlevels, you need to find out your distribution.

SUSE

You configure your runlevels using

yast2 runlevel

Red Hat

You configure your runlevels using

system-config-runlevel

Generic

chkconfig --list

will give you an output like this:

aaeventd                  0:off  1:off  2:off  3:off  4:off  5:off  6:off 
acpid                     0:off  1:off  2:on   3:on   4:off  5:on   6:off 
alsasound                 0:off  1:off  2:on   3:on   4:off  5:on   6:off 
apache2                   0:off  1:off  2:off  3:off  4:off  5:off  6:off