Some people want to avoid caffeine but still want to drink iced tea. Although there are decaf teas out there, I personally don't think they taste very good.
Herbs that I think taste good iced include spearmint, peppermint, lemon balm, the Monarda species (Bee Balm, Wild Bergamot, and Oswego tea) which taste a lot like Earl Grey, and lemon verbena.
A trick to make it taste like black tea: a caffeine-free herbal blend that tastes a lot like black tea is to use red rooibos and raspberry leaf. Add Wild Bergamot (Monarda fistulosa) if you want it to taste like Earl Grey.
If you want to make it taste like green tea, try green rooibos, which is rooibos that has been processed in a manner similar to Japanese green teas.
One of my favorite companies to buy bulk herbs from is Mountain Rose Herbs. The best option for herbs though, if you are able to garden, is to grow them yourself. Mint, lemon balm, and Monarda in particular grow very vigorously in most temperate climates. Raspberry leaf is also easy to grow yourself.