In addition to saving money and plastic cups (since we're using reusable containers here), brewing the night before saves time in the morning, and the coffee is so good it gives me something to get excited about in the morning (when usually all I do is whine about having to go to work).
What you'll need: ground coffee (for a French press, use a coarser grind than for espresso or a drip coffee machine), water, a French press (no French press? you could probably strain it through a couple coffee filters), a refrigerator and a vessel for your brewed coffee.
I use four scoops of coffee to about three cups of water, which fills my press. Then I let it sit in the refrigerator overnight (10-12 hours will do the trick), then press and pour in the morning. Coffee goes into a jar with a lid and then into my bag and I'm off to work with a bounce in my step and two bucks burning a hole in my pocket.
Extra credit: Make an extra batch of coffee and freeze into ice cubes to be added to your freshly cold-brewed coffee. Also, a dash of cinnamon added to your ground coffee before you brew it will perk up cheaper coffee (or live with someone who works at Whole Foods and brings home leftovers and doesn't drink coffee so you get them all to yourself).