Slinkachu is a UK based artist who creates street installations but on a very, very small scale.
From his bio:
"My 'Little People Project' started in 2006. It involves the remodeling and painting of miniature model train set characters, which I then place and leave on the street. It is both a street art installation project and a photography project. The street-based side of my work plays with the notion of surprise and I aim to encourage city-dwellers to be more aware of their surroundings. The scenes I set up, more evident through the photography, and the titles I give these scenes aim to reflect the loneliness and melancholy of living in a big city, almost being lost and overwhelmed. But underneath this, there is always some humour. I want people to be able to empathise with the tiny people in my works."
I really like the idea of street art and street installations that are minuscule and not immediately obvious.
I think it would be amazing to find one of these while walking around the city.