That all depends upon what packages you wish to use
Seriously.. That is one of the things that makes linux so great. You can pick and choose what YOU wish to use, not settle for what some company wants you to use.
It's kinda hard for someone else to tell you what you would find beneficial, not even knowing how you use your system. After all, there are over 20,000 packages in the online repos now.
I do know a few packages that I go back and install on just about every system I have.
gparted - an application to partition a disk and create a filesystem on them.
testdisk - useful in the even that you have partition data corrupted.
hdparm - listing and setting drive parameters.
I usually use an application called AutoPlus (look in the guides section of this forum) to install the audio/video codecs
I also install vlc as a media player. (it's in the rpmfusion repo)
Adobe flash player. (If you have 32 bit, you can use the adobe repo and install from there. If you have 64 bit, adobe just released a beta flash 11 for 64 bit.)
beyond that, it's more specialised depending upon what I am going to use that particular system for.