Anything you miss in Vocaddict? I'm always open to recommendations although I can't guarantee that I'll implement it.

A few commonly asked things on the to do list:

Intrinsic:
-- Stronger addiction
-- Optimizations for foreign writing systems
-- Statistics

Extrinsic:
-- Import of free language files
-- Mobile counterpart
-- Answer questions by typing
-- Support for sound
-- Crunch-Mode if you started studying late
-- Rewards less artsy and more mainstream