I wrote my own Golf GPS app last summer for the 7520. I just updated it for my new 8800. I think the 7520's screen is easier to read in the sunlight though.....
It's a pretty simple app, but the yardages are spot on using the gps.
It allows for multiple courses, and multiple targets per hole, i.e. sand traps, lakes, green center.
You can map the coordinates physically(by standing on the location) or by entering lat/long manually. I use the google earth sat view. It would be pretty easy to write an upload utility for google's kml format but I have not had time yet.
There is also no way to backup the course data, but that is only a problem if you update the os as it is stored in the gps api's landmark store...
Anyway, if there is any interest, I could probably put the ota download on one of my websites.
It definitely helped my game last year. Especially when your on the wrong fairway and need to know the distance