I have an idea of synching the time-stamps of the GPX waypoints (being created with GPS reciever) and the video captured by the digital camera of a device (having both GPS receiver and digital camera).
In this way video trails can be created which would show the exact video footage corresponding to the GPS coordinates of that place.
To achieve this creation of a application for the device which binds the flow of GPS data with the video being captured at that time.
Playing should be easy.When the video (having GPX data synched with it) is played then the corresponding location,altitude could be displayed as an overlay to Openstreetmaps.The video faeture could be embedded with openstreetmaps API.
Please give your suggestion on this idea its not implemented anywhere till now.It would be one step ahead of Geo-tagging.