  New enhancements in the charmonium and bottomonium spectra observed since
2003 are very briefly reviewed. Special attention is paid to $\chi_{c1}(3872)$
(formerly $X(3872)$) owing to its remarkable proximity to the
$\bar{D}^{\star0}\!D^0$ threshold, which allows modelling as a quasibound
axial-vector $c\bar{c}$ state with a large $\bar{D}^{\star0}\!D^0$ admixture.
In contrast, the interpretation of many other charmonium-like and
bottomonium-like states is still very controversial and some may not even
correspond to genuine resonances. Accordingly, several entries in the PDG
tables have been wildly changing over the years. Three representative states
are reviewed here as non-resonant enhancements due to threshold effects, viz.
$\psi(4260)$, $\psi(4660)$, and $\Upsilon(10580)$.
