If you're making your iced coffee with normally brewed coffee, you are a jive turkey.  But why switch, you may ask, if you're stubborn and set in your ways NOT THAT I'M DESCRIBING ANYONE HERE. 

Cold brewing coffee is so simple you will wonder why it took until 1964 for someone to think of it.  Take the coarsest ground you can get and dump it in a big pitcher of water at a ratio of 1:4.5 coffee to water.  Let it steep on a counter or fridge preferably overnight, but three hours works too, supposedly.  Filter the grounds out (this is one of the reasons you want a coarse grind).  Ideally you will have a mesh filter fine enough to handle it, but if not you can throw in a paper filter as well.  Now you have a pitcher full of flavor.  The only limit, quantity wise, is the size of your pitcher.

Now a word of warning, the coffee this makes is so smooth that you can easily just chug it straight.  It is delicious, and substantially less acidic/bitter than what you're used to.  However, this is also dangerous, because what you actually have is a concentrate that is about twice as powerful as normal coffee.  So if you pour yourself a giant mug you will be tweaking on the caffeine.  I'm used to the giant ones at Starbucks and one cup of this gives me a pleasant buzz.  However you can go easily up to 50/50 concentrate and milk (or water) and it will still taste just as much like coffee.  Throw a dash of blueberry syrup in there.

Also you can apparently use it as the base for your own frappucino style drinks but I've been too busy drinking it normally to worry about that.