I'd love to see an option added to the practice section to help us focus on a specific type of language skill.
Some examples might include:
Listening & Writing: Only the audio with no text, type the answer.
Visual recognition & Listening: Audio with no text, match the appropriate image
Visual recognition & reading: Same as above, but with accompanying text
Listening & Translation: Just audio, no text. Translate to English.
Reading: Translate text to English
All in all, Duolingo is shaping up to be one of the best language tools I've tried. But as with most, I find myself excelling in one area (reading/writing, for instance) and feeling a bit lacking in another (listening, for example). I think "practice skills" would be a great addition!