  The key contribution of the discovery of nuclear-powered pulsations from the
accretion-powered millisecond pulsars (AMPs) has been the establishment of
burst oscillation frequency as a reliable proxy for stellar spin rate. This has
doubled the sample of rapidly-rotating accreting neutron stars and revealed the
unexpected absence of any stars rotating near the break-up limit. The resulting
`braking problem' is now a major concern for theorists, particularly given the
possible role of gravitational wave emission in limiting spin. This, however,
is not the only area where burst oscillations from the AMPs are having an
impact. Burst oscillation timing is developing into a promising technique for
verifying the level of spin variability in the AMPs (a topic of considerable
debate). These sources also provide unique input to our efforts to understand
the still-elusive burst oscillation mechanism. This is because they are the
only stars where we can reliably gauge the role of uneven fuel deposition and,
of course, the magnetic field.
