In the last couple of week I added 3 new packages to my default install:
1.) atop is a very good extension of top, it includes disk and network utilization among other things.
2.) mosh is a ssh replacement / addon, that switches from TCP to UDP and makes it possible to keep you sesstion open even with a new IP address.
3.) lzop very fast compress/uncompress, very good for disc images via network.
My current default post install list for a Fedora or RHEL list is:
yum install iptraf acpid man bind-utils vim-enhanced nc zip unzip wget etckeeper links screen yum-utils lsof bash-completion ddrescue dos2unix dstat lftp links hdparm smartmontools jwhois kexec-tools mc mcelog memtest86+ mmv mtr nmap ntp openssh-server pbzip2 rng-tools sysstat vconfig vlock lzop atop mosh
I normally install minimal, so some of them are already installed in normal installations. I also added EPEL packages when on EL.