Software I use (and recommend)

vim

my main text editor for about 2 years now

dwm

the wm I use. It can be pain to setup, but otherwise works as it should.

dmenu

simple, but works as it should

feh

simple and fast image viewer, probably included with your distribution.

VLC

I’ve never used any other music player

mutt

terminal email client

tcc

just another incredible thing made by Fabrice Bellard

And software you probably already know like awk, ssh, rsync, R, latex, and git.