Sometimes dying people simply stare, often at a corner of the room, perhaps even waving.
Deathbed visions have been characterized as delusions. (But do not discount the possibility of a UTI.)
Visits by End Friends and other deathbed visions are described in this republished 1926 collection.
A list of websites on death and dying
A list of books on death and dying
Psychopomps are escorts to the after life. This PechaKucha presentation discusses the idea that no one dies alone.