High-dispersion spectroscopic observations of 77 Cygni, V815 Herculis, and HD 140122 have resulted in the detection of at least one additional component in each system. The newly identified component of 77 Cyg has a period of 35.48 days. V815 Her is a triple system with periods of 1.810 and 2300 days or 6.3 yr. The two visual binary components of HD 140122 are short-period spectroscopic binaries with periods of 10.879 and 15.770 days.

This paper presents some results of the analysis of the eclipsing binaries samples that came out as by-products of the OGLE microlensing surveys. These experiments monitored millions of stars in the direction of the galactic bulge (OGLE-I), and of the Small Magellanic Cloud (OGLE-II). Their completeness allowed the discovery of rare and interesting systems. An example is a new group of long period binaries in the SMC with presumably a giant component in contact with the critical lobe, which dominates the systemic light variation (“β -contacts”). These systems obey a period-luminosity-color relation and could be used as an auxiliary, but independent, tool for distance determination. Another very interesting object, for its implications in the studies of angular momentum loss processes by magnetic braking and of stellar activity, is the system of shortest known period with M dwarf components, discovered by OGLE-I, BW3 V38, that is the target of a spectroscopic follow-up. The perspectives for close binary star research in view of future space missions, such as COROT and Eddington are briefly discussed.

Improved orbital elements for ϕ Cygni have been determined from 47 new high-dispersion spectroscopic observations. The period and eccentricity are 434.14 days and 0.559, respectively. Minimum masses plus the inclination of the visual orbit result in masses of 2.16 and 2.06 M⊙ for the two giants. The small magnitude difference of 0.25 mag and a mass ratio of 1.044 indicate that both giants are most likely in the helium-burning phase of their evolution.

Orbital periods and other parameters of symbiotic binary systems in the LMC and SMC are presented and discussed. In particular, the symbiotic stars in the MCs are compared with those in the Milky Way.

We present population synthesis studies of white dwarf - main-sequence star binaries, of cataclysmic variables that are driven by circumbinary discs, and of eclipsing binaries in the exoplanet transit search SuperWASP.