Smoothing/generalizing polygon in QGIS?

Is it possible to smooth or generalize a polygon in QGIS, perhaps by using a plugin like the generalizer-plugin for lines?

I could convert my polygons to lines, smooth them and convert them back to polygons but this is not working for my polygons because of several reasons.

Answer

you can use:

Vector menu -> Geometry tools -> Simplify Geometries

.

Beside this you can use Douglas-Peucker algorithm in postgis too, so you can use in postgis then adding postgis layer to qgis. you can find some info here about Simplify: Reduce the weight of a geometry.

SELECT simplify(the_geom,500) as simpgeom 
    FROM neighborhoods