  We survey work on the paradigm called "computing by observing." Its central
feature is that one considers the behavior of an evolving system as the result
of a computation. To this end an observer records this behavior. It has turned
out that the observed behavior of computationally simple systems can be very
complex, when an appropriate observer is used. For example, a restricted
version of context-free grammars with regular observers suffices to obtain
computational completeness. As a second instantiation presented here, we apply
an observer to sticker systems. Finally, some directions for further research
are proposed.
