Francois Orsini is working on JavaDB, a derivant of the Apache Derby RDBMS. In one of his recent articles he is talking about the possibility of using JavaDB for offline AJaX. This is - as far as I am concerned - a very promising step in the right direction: We all love the rich UI that AJaX can provide - the problem is only when we are offline, all those applications do not work anymore. By caching the various requests on the client and synchronizing them upon reconnect, you can make web applications into real applications. As Francois points out, this can be achieved by simply modifying the client side call behavior (check if connected -> synchronize -> use local copy).

I would have a whole bunch of applications that would be useful:

• Calendar
• Email
• Spreadsheet & Word Processing
• Bloging
  

Actually, with these four applications I could do about 60% of my work offline - as long as I have a browser that is AJaX and JavaDB enabled.