  Since the launch of INTEGRAL in 2002, about 300 new sources have been
discovered. Understanding the nature of these objects is of prime importance
for many aspects of astrophysics, such as the evolution of stars, population of
sources (Galactic and extra-Galactic), and ultimately the physics powering
them. However, their nature cannot be established from the soft gamma-ray
observations. The first step towards unveiling the nature of those sources is
to refine their X-ray position, in order to finally find counterparts at other
wavelengths. X-ray spectra are also of prime importance to obtain clues on the
nature of the objects. Since the discovery of the first IGR in 2003, our group
has been active in several aspects of these studies. Here, we present the main
results we have obtained through 7 years of multi-instrumental (Chandra, XMM,
Swift, RXTE) campaigns.
