in the later versions of Google Earth the ruler tool gives you the bearing in degrees + distance of a line you draw between two points.
lisi4king, you can display any image fixed as a "screenoverlay" in Google Earth. If you open thanhbdt's kmz archive in 7zip, you can extract the .kml file and associated image file (.kmz is basically a zipped format of .kml). If you open the .kml file in notepad you will get the following .kml code:-
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.2">
<ScreenOverlay xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
<name>Compass Tool</name>
<description><![CDATA[This tool can be used to obtain a fairly accurate compass bearing from one location to another. To use:
<ol>
<li>Click <b>N</b> on the navigation tool to orient the Google Earth view to north, and return the view to straight down. (Unless hot keys have been modified, pressing the <b>R</b> on the keyboard will accomplish both.)</li>
<br><br>
<li>Go to close-in view of the point of origin and activate the <b>Ruler</b> tool.</li>
<br><br>
<li>Extend the <b>Ruler</b> line to the second point.</li>
<br><br>
<li>If necessary, zoom in or out until the <b>Ruler</b> line crosses the compass scale.</li>
</ol>
<br>]]></description>
<drawOrder>99</drawOrder>
<Icon>
<href>files/rosa02.gif</href>
</Icon>
<overlayXY x="0.5" y="0.5" xunits="fraction" yunits="fraction"/>
<screenXY x="0.5" y="0.5" xunits="fraction" yunits="fraction"/>
<rotationXY x="0.5" y="1" xunits="fraction" yunits="fraction"/>
<size x="-1" y="-1" xunits="pixels" yunits="pixels"/>
</ScreenOverlay>
</kml>
In this case the image to be displayed as a "screenoverlay" is "rosa02.gif", a gif image of a compass with transparency. You could replace this image with any other raster image and it should get displayed fixed in the middle of your Google Earth screen.
If you wanted an image displayed as a fixed overlay on the top left of your screen, then you would use the following kml code, where your_screenoverlay.gif is the image to be displayed. This could be a jpg, bmp, png or any raster image that Google Earth can open. gif and .png can of course have part of the image transparent (like the compass example above).
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.2">
<ScreenOverlay>
<name>your_screenoverlay.kml</name>
<drawOrder>99</drawOrder>
<Icon>
<href>your_screenoverlay.gif</href>
</Icon>
<overlayXY x="0" y="1" xunits="fraction" yunits="fraction"/>
<screenXY x="0" y="1" xunits="fraction" yunits="fraction"/>
<rotationXY x="0.5" y="0.5" xunits="fraction" yunits="fraction"/>
<size x="-1" y="-1" xunits="fraction" yunits="fraction"/>
</ScreenOverlay>
</kml>
Hope that helps, Stan.