GEO 600
LIGO [Laser Interferometer Gravitational-Wave Observatory]
LISA [Laser Interferometer Space Antenna] (see also here and here).
LSU Gravitational Wave Experiment (Louisiana State University)
MiniGRAIL [Gravitational Radiation Antenna In Leiden]
Rome gravitational wave research group
TAMA Tokyo Advanced Medium-scale Antenna
VIRGO
Other gravitational physics activities (see also here).