There is also a Joomla chatroulette clone that is easy to install as Joomla component and provides simple implementation for Joomla users.
It was a genius idea, and they used it to launch their site, but sadly this feature that made them so famous was removed, and now it's a site based around paid lessons, although it does have some limited free chat room functionality.
Being based on 2 Way Video Chat - a professional reliable 1 on 1 webcam chat solution, there are some important functional improvements.
At any time, either user may end the session and start a new one with another random user.
If you're ready for a unique experience rife with peril and amusement, see Step 1 below to get started, brave internet pioneer!
For now, I'd highly recommend you go to italki for a better way of finding free and affordable teachers of all languages.
Here is my detailed and up to date review of italki.