ZDT has functions for entering flashcards, studying them in Self Review, Pinyin Recall and Definition Test. Users can import or input their own flashcards. It is possible for users to export their flashcards to import them in another ZDT instance. This way, I was able to share my lists with co-students. It can also import from a text with custom format, supports UTF-8, UTF-16, Big-5 and two other codings. I use that a lot, because I type the list into excell, then save it as Unicode. That was easier, because some lists were already available on the web. The review can be filtered with an interval or a smart filter. With the interval filter, the interval of cards that are answered correctly increase with 1, 3, 5, 7, 10, 14 .... days. This function completes the pogram, making it an effective study tool. The number of days is configurable. I am using ZDT for a year now, and besides some minor problems (which are being fixed at the time of writing) with great satisfaction. The program has some extra plug-ins (the flash card system itself is a plug-in), like an Anotator and a Dictionary, which I do not really use. I am planning to memorize the built radicals list though, since sometimes it is just really useful to know them. Highly recommended application.
Very nice app :)
Nicely coded, functions well, has all the features I need. And it's open-source :-) Really awesome! Too bad the original author has stopped developing it.