You might be interested in the projects Maps on a Stick and MapBox iPad. (disclaimer: designed the former, involved in the latter. however, both are BSD-licensed, and the underlying tile format, termed ".mbtiles", is SQL-based.)

Maps on a Stick is an offline OpenLayers map. The main reasoning for going with a portable database/server instead of client side storage is that using browsers as large data storage isn't quite worked out and populating and indexing the cache can be costly.

Offline tiled map web app
I've been wondering this for awhile now. Is it better to scan a 35mm negative, or a larger print from the negative? Which will provide a better scan? Does this change when moving to a larger film, like 120 or 4x5?
