I frequently make all-herbal iced drinks. My favorite ingredients are green rooibos, lemongrass (fresh or dried), lemon balm, lemon verbena, or lemon myrtle, spearmint...and a little bit of cardamom.
In terms of actual tea, I've had good luck icing bancha, as well as a variety of different Chinese teas, including mao feng and (inexpensive, lower grade) bi luo chun. I usually don't use the most top-notch tea for icing, instead using good, but not outstanding stuff. I actually ice green tea more than black. Sometimes I ice Assams or Yunnans. I tried icing oolongs but wasn't crazy about it.