H.E.S.S. (High Energy Stereoscopic System) is an array of five Cherenkov telecopes located in the Khomas highlands in Namibia. We observe gamma rays in the range from a few tens of GeV to 100 TeV, allowing to see lots of sources : pulsar and black holes environments, supernova remants, external active galaxies, ... The H.E.S.S. instrument allows us to perform other kinds of measurements such as the flux of cosmic electrons, and search for dark matter, axions, test for the Lorentz invariance principle, etc.
Find out more about H.E.S.S. here.
CTA is a project of construction of a large array of Cherenkov telescopes. There will be two sites, one in each hemisphere, and construction should start in 2016. Compared to H.E.S.S., CTA will have a ten-fold increased sensitivity and a better angular resolution.
Find out more about CTA here.
IAXO is a project for the construction of a large helioscope. This kind of instrument is dedicated to the search for axions and other types of low-masses scalar particles. The idea is to look at the Sun with a big magnet. If axions are thermally produced in the Sun, our magnet would convert them into observable X-ray photons. CAST is a currently running helioscope at CERN, see here. And here is the IAXO web page.
MadMax is a project to detect axion dark matter using large dielectric plates within a magnetic field. I am also involved in more marginal attempts to build axion dark matter experiments using large metalic mirrors.