Probably not very well known outside Japan: Hoji-cha, a green tea roasted over charcoal at high temperatures. Because of the roasting the color of the leaf changes from green to reddish-brown.
Hoji-cha is made from the lower parts of the bush, the stem (karigane). Because of this and the roasting, this tea contains little catechin (causes the astringency/bitterness of green tea) and caffeine. I love the sweet smokey flavor of this tea.
Hoji-cha (or spelled as: houjicha) can be used to make iced tea. The traditional way is to boil water in a kettle, add the leaves (according to taste) and boil for another 2 minutes. After cooling, chill the tea in the fridge. Without the leaves, of course.
Green tea like sencha or gyokuro is also perfect for iced tea. For the best 'green & vegetal' taste I steep mizu-dashi-cha for a long time in cold water: I add one tea bag of mizudashicha from Maiko Tea Shop to 500 ml - 1000 ml of water, and keep it in the fridge for about 8 hours, or overnight. You can use any green tea, but mizudashicha is stir-steamed extra deeply before drying, thus making it more suitable for extraction in cold water.
I can't imagine a summer without iced tea. It's cheap, easy to make and healthy since it doesn't contain any sugar. But you have to use really fresh tea – buy it in Japan from an online shop! – for the best taste and fragrance.