A combination of Silverlight with Google Gears?
In the comments he responds about the benefits, etcâ€¦
â€¦ simply put, the Silverlight isolated storage provides the analogous of straight file I/O. You can squirrel away data and retrieve it later. Gears does the same thing conceptually but it provides a backing database (SQLLite) as persistence store and the benefits of a query language like SQL for data retrieval, filtering and transformation.
Interesting to see, basically giving Silverlight â€˜offlineâ€™ capability outside of the Isolated storage. (Iâ€™m not sure the size limitations for Gears).