Is there any way we can contribute to duolingo?
I would think suggesting web pages, because the ones that come up automatically tend to be garbage - a few sentences, or repetitive, or containing bad formatting (a caption spilling into an article). I've only been on a few weeks, but I've been less than impressed by that aspect.
Translating a lot of webpages through it ("real world translation" button) is the obvious way. For other kinds of contributions you have to ask the staff. Dou you mean things like manual filtering of feedback messages, administration, web developement?