Did I mention that simpleTAN is available in english? At the moment we are working on translating the website but it seems to take us longer than we thought. But if you want, you can give the app a try. A short description is available via this recent Blog Post. Enjoy using it :).
Edit: simpleTAN isn’t available anymore. The project has been closed. If you are interested in it give me a shout and I’ll send you a copy. But I’m pretty sure it won’t run on OS X >= 10.5.7