Cool UNIX stuff
rsync -av --progress [--delete] sourcedir user@host:remotedir
Makes remote directory look exactly like source directory (or vice versa!) including permissions, ownership, etc. Useful for transferring many files without creating a tar or doing a bunch of scp commands.
grep --color -E 'keyword'
Highlights keyword in a grep (useful for looking for stuff while tailing logs.)
Great collection of CLI tools and trinkets.