Here are some applications which have been pared down to the best and the most essential.
ClamTk: The likelihood of suffering due to infected files is less on Linux but by no means an impossibility. The ClamTK is a great graphical front end for the robust ClamAV providing a lightweight protection and has regular updates for definitions
GParted: offers easy to use interface for a simple and usable partition editor which can be used with the least fuss to get things done. You can also clone partitions and image disks.
Kate: This is an expert text editor for programming that is essential for a coder to have. The syntax highlighting stretches and covers more than 200 types of code file.
Libre Office: This one has enables spreadsheets, word documents and presentations and what is more it is also compatible with Microsoft word/excel/powerpoint.
LuckyBackup: This is a utility that provides backup the conventional way and can be easy to use. The options that you have are clear letting you achieve anything from one-sided copy to incremental two-way synchronisation.
PeaZip: It is an archive manager that supports RAR extraction and also allows you to create and manage over 150 archive types.
Shutter: Shutter is an excellent option for taking screenshots. It has many features and can be very quick. You can click particular areas or individual windows or the whole desktop. What is more it also transfers the shot to the editor for further work.
SMPlayer: This one is quite compatible no matter where you want to run it and it also supports almost all formats. It also has the ability to memorize setting on file to file basis. If stopped it will start playing at the same place where it was stopped.
Synapse: It is a responsive launcher that is not cumbersome and works very quickly.
Synaptic Package Manager: This used to be a feature of Ubuntu till it was replaced. Synaptic Package Manager is the way to go if you want to run software from 3rd party sources