Quantum theory offers not only nonlocal correlations, but also other bizarre features that do not seem to fit well with our intuition. For instance, our everyday experience is that reading off the time from a clock does not stop it from ticking, but quantum theory dictates that any observation (interaction) with a quantum system necessarily perturbs its evolution. The quantum zeno effect in particular forbids the state from evolving if the system is being measured all the times. How do we reconcile this "disturbing" feature of quantum theory with our everyday experience? Meanwhile, quantum information has taught us that quantum effects can also serve as powerful resources. Our goal here is thus to identify features of the theory that are fundamentally different from our classical intuitions, and in particular quantum effects that are useful, for instance, for future technologies.