A rather grim one I found in Sicily last year was https://en.wikipedia.org/wiki/Alitalia_Flight_4128, I could see the exact coordinates on the mirrorspace map where the plane went down...
I also think a hosted version, or secure (yeah I know) account for personal geospatial note type things would be useful; e.g. mark a location for a reminder to do something the next time you are nearby (store X has a sale, location Y has live music daily at 1300)