To me, initially it was unclear when somebody would want to use this. After some thought I figured that something like this could be cool for a tech document or white paper you're reading online with a lot of unfamiliar or esoterically techie jargon in it.

So people who have to read about difficult concepts in varied areas may find this useful. This could be anyone from students to professional consultants. So finding forums where students are trying to get help with various topics could be a good place to start.