You can easily make a map with multiple markers and descriptions at Mapfaire. No registration is required. You can’t add images right now, but apparently that feature is in their future plans.
I’m adding it to The Best Map-Making Sites On The Web.
Thanks to Google Maps Mania for the tip.
(Please note that Daniel Callahan reminds me that you have to be signed-into Google in order to use the service. That had gotten by me originally)