This ModelAdmin class sets fields for models saved in admin corresponding to the user that created the object and the user that last updated the object. Trivial for the current model, but a little more involved to make it work with inlines.
The fields still show up as drop-downs (`select`) in the admin, but I fixed that with a little jQuery:
$(function(){
$("select[id*='creator'], select[id*='updater']").each(function(){
var user = $('option:selected', this).text();
$(this).siblings('.add-another').hide();
$(this).hide();
$(this).after(user);
});
});
This could easily be subverted, but with trusted users, it makes for a quick and dirty read-only field.