I think the first and most famous of them — Chat roulette. It’s more a video chat, although chat without a camera there too. Throws you to a random person and if You like it, just please, anything to write. Otherwise, after a few seconds You’ll drop to another source. There is a built in graphic editor so that communicate where you can, not only printing of letters but also drawing.
With regards to the audience, it is very extensive, so for full use of this service you must be at least a little knowledge of English. However, you can use the analogue Video chat with a predominantly Russian-speaking audience.
Talk to me chat without registration, all you need to do is follow the link and click on one button and You have the source. Nothing in excess, just communication. At the time of me writing this post there were 111 users online.