The Tutor Crowd promotes its free English tuition trial by taking their work to the streets. Finding spelling and grammar mistakes in graffiti throughout London, the online classroom service has marked up words and phrases that need correction. The Tutor Crowd's Tumblr says, "English tuition doesn't have to be stuffy, boring, and expensive. At The Tutor Crowd, we're taking the classroom to the streets, correcting London's graffiti to spread our message."

[via Creative Review]