How do I display the Image of an Author in a post? This might be a stupid question... but I can't seem to figure it out. 

I'd like to show the photo of an author beside their entry. I thought the proper variable was... 

{{user.photoUrl}}


...until I logged out and my photo disappeared.
That will get you the url of the current user's photo. To get an author's photo do this:

{{ author.photoUrl }}


If the author is not defined in your context but the entry is, then get the entry's author's photo as follows:

{{ entry.author.photoUrl }}