Optical spectroscopic monitoring of southern galactic O and WN Stars: the discovery of new binaries and trapezium-like systems R. Barbá, R. Gamen, J. Arias, N. Morrell, J. Maíz Apellániz, A. Sota, N. Walborn, E. Alfaro. We are conducting a spectroscopic monitoring of galactic O and WN stars from the Galactic O Star Catalogue (GOS, Maíz Apellániz et al. 2004) and VII Catalogue of Galactic Wolf-Rayet Stars (van der Hutch 2001, 2006). The survey was officially started in 2005, and so far we have collected about 2000 spectra of 210 O and WN stars using La Silla, LCO, CTIO (Chile) and CASLEO (Argentina) facilities. This huge spectroscopic dataset (which is enlarged with spectra obtained during the last 10 years in CASLEO, and some more retrieved from the ESO Archive) has allowed us to discover about 30 binaries with orbital periods spanning from 1.5 to hundreds of days days. Among them, it is interesting to mention the massive binary systems WR 25 (Gamen et al. 2006b), WR 21a (Niemela et al 2008), HD168075, HM1-8, and HD150135. The latter two objects were found to be massive SB2 binaries (minimum masses 31M +15M and 70M +26M respectively), with HD 150135 being a probable multiple system. We draw a special attention to the ZAMS star Herschel 36 (the ionizing source of the Hourglass Nebula Cluster, HNC). The HNC resembles in many senses the Orion Nebula Cluster, with Her 36 playing a similar role to that of Tetha1 Ori C. We have discovered that Her 36 is composed of at least three spectroscopic components (Arias et al. submitted). These kind of massive trapezium-like young systems are potentially interesting sources for VLTI facility. Additionally, nearly 110 stars show RV variations greater than 10 km/s for which periods have not yet been determined. The kind of RV variations that we found in some of these stars seem indicate long period binaries. Also, the Northern hemisphere part of the sample is being observed from the Obs. Sierra Nevada, using the 1.5-m telescope and Albireo spectrogaph, and Calar Alto (Spain), using the 3.5-m tel. and TWIN spectrograph. We have observed the 95% of the targets in the GOS v1.0 and we have already started to observe targets in GOS v2.0 (Sota et al. 2007). We are preparing a web-site to offer to the community the observed spectra and additional VO services. A pre-release of data will be available at http://ostars.dfuls.cl/ownsurvey.