To troubleshoot WFS server (geoserver) with big dataset (global OSM btw) I have tried number of free GIS desktops which work on Mac: QGIS (1.8, 1.9dev), uDig, gvSIG - none of them seems to support WFS request filter for currently visible area. Which makes them quite unusable for any bigger work datasets. QGIS used to have "Only request features overlapping the current view extend", which should be exactly what I'm looking for, but this seems to have disappeared.