Brief introduction: In the old version, the GPS tag is inserted into the photo with a third-party tool, and using Java to match the log entries with photos. In the new version, I wrote a C# program to do the entire job. The algorithm is improved. It's way faster and easy to make changes. I bought a new GPS logger unit. It is small sized and light weighted, so that I can carry it with me while I am taking photos. My C# program will match the log entries (NMEA) with the photos, and insert the GPS info (EXIF) into the photo. A watermark is added as well to notice the users.
Example: There are 2 ways to use this online application (written in PHP). One is to enter the photo's (GPS tagged) URL address into the field above, and click the button. The other way is to include the photo's URL in the link. The key is "img", and the value is the photo's URL. (http://www.sunnyspeed.com/gps?img=GPS_tagged_photo_URL) This allows you to share your photo with your friends. Some photos with GPS tagged are shown below. (Click on the photos)
More GPS tagged photos, go to 
2008-Oct-13. Thanksgiving