Not an iced tea per se, but for a cold refreshing summer drink I've started to put ice cubes on some Uji sencha. It opens up a whole new range of flavours I hadn't noticed before.
The actual method is called Shinobi-Cha, and all I know about it I learned from this video here: http://www.youtube.com/watch?v=4UEZcq1qVtw
Admittedly, the amount of liquor produced is minute, and takes a long time. I also cold brewed silver needles once, but something seemed off. Since then I got it in my head that some bitter flavour was created by the surface of the glass