I once wrote https://github.com/darius/spaced-out which is certainly not serious competition, but came from a similar idea: build the deck from the most common words in the language (automated using an aligned parallel corpus), and replace the Anki interface because I didn't like it.

It's probably a better starting-point than starting from scratch, I'll say that for it. (I wasn't interested enough in language-learning to take it further.)