Here's one of my own projects - a map currently showing over 400 videos from around the world.
Essentially that is it- just an interesting way to explore the world with Google Maps and YouTube. However I thought it might be useful to take you through some of the tools that I used in building this map.
Donkey Magic Map Maker
There are a lot of very useful Google Maps creation tools available. I used Donkey Magic Map Maker to help me create this map because I find it one of the simplest and easiest to use.
Using Donkey Magic Map Maker it is very easy to add map markers and, when you have finished adding all your markers, you can just cut & paste the html for the whole web page including your Google Map.
To complete a map all you need to do is add your own Google Maps API key.
Google Maps Lat / Long Bookmarklet
If your map contains a large number of map markers it is best to use marker clustering. For the Video Map I used MarkerClusterer as it is one of the more attractive looking of the clustering libraries available for the Google Maps API.
Finally, to refine the look of the map I changed the custom Google Maps icon to one from the huge google-maps-icon collection. The google-maps-icon collection currently host over 900 Google Maps icons, which normally ensures that you can find at least one to meet your requirements.