How to make your Mac say anything

While reading Lifehacker's top 10 list of "things you forgot your Mac can do", I came across this neat little Terminal command that allows your Mac to "say" anything:

1. Open Terminal
2. Write "say" and then a sentence of your choice
3. That's it :-)

You can even have it read a whole text file with this command:

say -f mytextfile.txt

Totally useless but funny as hell (depending on what you're telling it to say) :-)