  Bernoulli convolutions form a one-parameter family of self-similar measures
on the unit interval. We suggest to study their two-dimensional density which
has an intricate combinatorial structure. Visualizing this structure we discuss
results of Erd\"os, J\'oo, Komornik, Sidorov, de Vries, Jordan, Shmerkin and
Solomyak, Feng and Wang. We emphasize the r\^ole of finite orbits of associated
multivalued maps and mention a few new properties and examples.
