Users can submit their BrainyPic or Flix after a simple sign up or by using Facebook Connect. Sign-up also gives users access to voting and comments.
BrainyPics asks users choose a word from a drop down menu "word bank", upload a picture, give credit to the photos source :), and then write a caption using the word correctly. Flix uses a similar word bank, but videos must be uploaded to a video host like YouTube and then embedded. Submissions receive votes for being either a "great sentence" or "questionable usage", or users can add comments.
"Don't say anything you wouldn't say to your mom" - may not stop comment abuse but it's a good reminder.
This is a great example of students creating their own learning resources and combines basic social networking features that make the site engaging and collaborative. I only wish I could add the word "repertoire".