Is there a way to filter a queryset in the django admin?

It's not documented, but the standard changelist view accepts normal queryset filter parameters as GET arguments. So you can do:

/admin/myapp/bar/?user__username=foo

All you need to do is override the get_queryset() method on your ModelAdmin. Something like this:

class ThisAdmin(admin.ModelAdmin):
    def get_queryset(self, request):
        """
        Filter the objects displayed in the change_list to only
        display those for the currently signed in user.
        """
        qs = super(ThisAdmin, self).get_queryset(request)
        if request.user.is_superuser:
            return qs
        return qs.filter(owner=request.user)

The advantage of this approach is that it doesn't clutter up your nice pretty admin URLs (and also, therefore, make it extremely obvious to your users how to view other people objects).