Some experiments show that to get best results with OpenOffice.org (and probably other packages), X server's DPI value should be set to real monitor DPI.
XFree86 seems to have an excellent way to do that. In XF86Config-4, in section "Monitor", one can write DisplaySize 320 240 and specify physical monitor dimensions that way. Using that information, X server will calculate correct DPI value. Some modern software (xft/fontconfig-based) uses Xft.dpi resource; this may be set by adding something like dpi=`xdpyinfo | awk '/resolution/ {split($2, x, "x"); print(int((x[1]+x[2])/2))}'` echo "Xft.dpi: $dpi" | xrdb -merge to /etc/X11/Xsession.d/95dpi Perhaps a question about physical monitor dimensions should be added to xserver-xfree86 debconf templates. It should have pre-defined values for common situations (such as 320x240 mm for 17'' monitors), and allow user to enter explicit values if he wishes (or not to set DisplaySize at all). I believe it's much better than just assume 100dpi by default (as it is now).