/etc/inputrc "connects" PgUp and PgDwn to "beginning-of-history" and
"end-of-history". It would be much more useful if these were
"history-search-backward" and "history-search-forward". Maybe "beginning-"
and "end-of-history" could be reached with modifiers.

Another point is that users' .inputrc files are ignored. It is trivial to
do something like this:

--- 8< --- /etc/profile ---
if [ -f ~/.inputrc]; then
  INPUTRC=~/.inputrc
else
  INPUTRC=/etc/inputrc
fi
export INPUTRC
--- 8< ---

Bye,
Nils