Wow - after quite some odyssey I found the culprit(s):

-r--r--r--  1 root  wheel  8239 Jun 10 21:07 lib/modules/input/acecad_drv.o
-rwxr-xr-x  1 root  wheel  139425 Feb 24  2002 lib/modules/input/calcomp_drv.so*
-rwxr-xr-x  1 root  wheel  176240 Feb 24  2002 lib/modules/input/citron_drv.so*
-rwxr-xr-x  1 root  wheel  141761 Feb 24  2002 lib/modules/input/digitaledge_drv.so*
-rwxr-xr-x  1 root  wheel  136398 Feb 24  2002 lib/modules/input/dmc_drv.so*
-rwxr-xr-x  1 root  wheel  135269 Feb 24  2002 lib/modules/input/dynapro_drv.so*
-rwxr-xr-x  1 root  wheel  141777 Feb 24  2002 lib/modules/input/elographics_drv.so*
-rwxr-xr-x  1 root  wheel  147400 Feb 24  2002 lib/modules/input/hyperpen_drv.so*
-rwxr-xr-x  1 root  wheel  143913 Feb 24  2002 lib/modules/input/microtouch_drv.so*
-rwxr-xr-x  1 root  wheel  228101 Feb 24  2002 lib/modules/input/mouse_drv.so*
-rwxr-xr-x  1 root  wheel  146098 Feb 24  2002 lib/modules/input/mutouch_drv.so*
-rwxr-xr-x  1 root  wheel  137634 Feb 24  2002 lib/modules/input/penmount_drv.so*
-rwxr-xr-x  1 root  wheel  135015 Feb 24  2002 lib/modules/input/spaceorb_drv.so*
-rwxr-xr-x  1 root  wheel  147161 Feb 24  2002 lib/modules/input/summa_drv.so*
-rwxr-xr-x  1 root  wheel  126239 Feb 24  2002 lib/modules/input/void_drv.so*
-rwxr-xr-x  1 root  wheel  174296 Feb 24  2002 lib/modules/input/wacom_drv.so*

Obviously leftovers from some ancient X version. I suppose those should be
properly obsoleted?

Martin