I tried Scratch at first but it wasn't realistic to expect schools to create maps that involved a relatively complex piece of programming. For a while it looked as if Zeega was the answer but the new version of their editor doesn't allow multiple links on a page. I had high hopes that the updated Google My Maps would allow more media to be attached to the map pins - in vain.
Time after time I returned to the simplicity of, the thoroughly excellent, Padlet. A map could be screen captured and used as wallpaper on a padlet wall. Images, video and sound files can be simply added as small stickies to the wall and, when clicked, open in a fair sized media player. Padlet walls can be password-protected.
So I'm not absolutely sure how I re-discovered Zeemaps. I first came across this app early last year when the plan was to create an interactive map of St Felix Middle. It did not do the business then (adding hyperlinks to Glogster web pages) and I suspect I gave it only a cursory glance recently. Had I spent a little more time I might have saved myself a good few hours of hunting and testing.
Zeemaps is based on Google maps but adds some interesting customisations. Map pins can be annotated, and audio, an image and a Youtube embed added to the information bubble. The pins can be customised to allow the use of your own icons, like my birds below (update 23.09.2013: this feature is now pay-for only - see comments below). There is a range of ways to share: including of course, web embedding. In order to keep the service free it displays ads (much less obtrusive in a full screen view) It is possible to pay the ads and Zeemap logo to go away though this is relatively expensive especially if you are planning to make several maps.
My Wish List:
To be able to make the Satellite view the default - I haven't found a way to do this yet (update 03/07: can be done via the "settings/display" command).
To be able to add links to the information bubble (update 03/07: this is possible but via an anonymous "website" link - it would be good to be able to name the site).
To be able to include a panorama viewer like the one provided by Photosynth so that you can create a sort of personalised Streetview or, failing that, a slideshow.
It makes a great way to display data collected in the field, though I reckon it would be possible to make a treasure hunt or mystery story. How would you use an interactive map?