Balloons in Google Earth are a great way to provide information about a place. Balloons are pretty easy to make. You just write text or html into the Description of a placemark using Google Earth.
Making your balloon really nice takes some more work. You can add really nice html, but this takes time and an understanding of html and css.
Shape2Earth for PowerPoints simplifies things by letting you create the balloon in PowerPoint, and then plot a point on the map with a graphic of the PowerPoint inside that points balloon.
First, select the slide you want to put in the balloon in PowerPoint, and then select the 'Balloon' button from the 'Shape2Earth' menu in PowerPoint (requires that Shape2Earth for PowerPoint has been installed). This will open up the Google Earth design globe in PowerPoint. Zoom to the area where you want to place the slide, and then click the 'Balloon' button on the toolbar in the design globe. Then, simply click on the globe to map that slide.
You can add as many slides and points as you would like. If you make a mistake, you can right-click on the placemark in Google Earth, and select 'delete' from the context menu. You can also click on the point to see what the balloon looks like (see below).
When you are done mapping slides, click the Export to Google Earth button to export to Google Earth
All the mapped slides will be bundled into a KMZ that can be easily redistributed.