Teavana app. That is, until I found Teaity.
It is a web based timer so it works both on my computer and on my phone. That makes it convenient and easy to use whether I am sitting on the couch at home, at my desk at work or if I'm on the go. The home page offers generic timers for each type of tea but the times are easily altered to your needs with a simple click. They also have a growing database of teas so that I can search for the specific tea that I am steeping. I think that Teaity will have some really exciting things in store for the tea community in the future and I can't wait to see where they go with it.
You can find out more about Teaity here.