  We are conducting a planet search survey with HARPS since seven years. The
volume-limited stellar sample includes all F2 to M0 main-sequence stars within
57.5 pc, where extrasolar planetary signatures are systematically searched for
with the radial-velocity technics. In this paper, we report the discovery of
new substellar companions of seven main-sequence stars and one giant star,
detected through multiple Doppler measurements with the instrument HARPS
installed on the ESO 3.6m telescope, La Silla, Chile. These extrasolar planets
orbit the stars HD 1690, HD 25171, HD 33473A, HD 89839, HD 113538, HD 167677
and HD 217686. The already-published giant planet around HD 72659 is also
analysed here, and its elements are better determined by the addition of HARPS
and Keck data. The other discoveries are giant planets in distant orbits,
ranging from 0.3 to 29 MJup, in mass and between 0.7 and 10 years in orbital
period. The low metallicity of most of these new planet-hosting stars
reinforces the current trend for long-distance planets around metal-poor stars.
  Long-term radial-velocity surveys allow probing the outskirts of extrasolar
planetary systems, although confidence in the solution may be low until more
than one orbital period is fully covered by the observations. For many systems
discussed in this paper, longer baselines are necessary to refine the
radial-velocity fit and derive planetary parameters. The radial-velocity time
series of stars BD -114672 and HIP 21934 are also analysed and their behaviour
interpreted in terms of the activity cycle of the star, rather than long-period
planetary companions.
