Solution 1:

Simply add aliases in ~/.bash_profile:

If the file .bash_profile doesn't exist:

touch ~/.bash_profile

Then add aliases with nano ~/.bash_profile. Examples:

alias ssh01='ssh xyx@xy'
alias ssh02='ssh -NC user@xy -L 9999:localhost:3306'

Then source the file or restart Terminal.app:

source ~/.bash_profile

Entering ssh01 in the shell will then execute ssh xyx@xy or ssh02 the second command.

The alias (i.e. ssh01) mustn't be another valid command in your path (e.g ssh-add)