App ideas - free of charge

Idea: Implement loading tiles along a GPX track into openstmap. So essentially set a scale, move along the track and upload as many tiles as are needed to cover the track in every direction. That would be great for using it as a background for gpstrek or similar apps. I have a implemented a prototype of using openstmap as background for my overview map, but getting good coverage for longer tracks is slow (as in upload time) and needs lots of storage.