  Dielectronic recombination (DR) of few-electron ions has evolved into a
sensitive spectroscopic tool for highly charged ions. This is due to
technological advances in electron-beam preparation and ion-beam cooling
techniques at heavy-ion storage rings. Recent experiments prove unambiguously
that DR collision spectroscopy has become sensitive to 2nd order QED and to
nuclear effects. This review discusses the most recent developments in
high-resolution spectroscopy of low-energy DR resonances, experimental studies
of KLL DR of very heavy hydrogenlike ions, isotope shift measurements of DR
resonances, and the experimental determination of hyperfine induced decay rates
in divalent ions utilizing DR.
