What a busy week! Found a cool Leaflet plugin, wrote a new Leaflet plugin, ... and finally put the polishing touches and refactoring onto a pet project from almost two years ago!
This Leaflet layer plugin extends L.TileLayer to add on-device caching of tiles, then the ability to switch between online mode (from web using the URL given) and offline mode (the on-device stash). Utility functions are provided to calculate tile pyramids, to accept arbitrary lists of XYZ ordinates,to view the cache usage, and to empty the cache.
If you make Leaflet maps for use with Cordova or Phonegap, you'll be interested in this!