Install figlet:
sudo apt-get install figlet
Now just run figlet with an appended text string:
tdd@tdd-laptop:~$ figlet wiki.lnxgeek.org _ _ _ _ _ __ _(_) | _(_) | |_ __ __ ____ _ ___ ___| | __ ___ _ __ __ _ \ \ /\ / / | |/ / | | | '_ \\ \/ / _` |/ _ \/ _ \ |/ / / _ \| '__/ _` | \ V V /| | <| |_| | | | |> < (_| | __/ __/ < | (_) | | | (_| | \_/\_/ |_|_|\_\_(_)_|_| |_/_/\_\__, |\___|\___|_|\_(_)___/|_| \__, | |___/ |___/
figlet has many options, checkout the man pages.