Ever needed to add a package by command line but not been able to remember what its called.

start typing your apt-get line

sudo apt-get install mysql

once you have typed as much as you know, push tab twice.
This will give a list of all the packages available.

Be sure you type as much as you can before pushing tab twice or you may get a lot of results.
The system will warn you first though eg.

user@example:~$ sudo apt-get install my
Display all 259 possibilities? (y or n)