Looking for a "stand alone" database

[Adams-Blake Co.]

MySQL and Postgre are good, but they are overkill for my application. What 
I need is something like MS Access... somthing that will handle basic SQL 
joins and something that is easy for the user to install. MySQL goes in as 
a "service" and most customers will never be able to get it installed... 
and I don't know of an installer that would do it in Windows, Linux, and 
Mac OS X. 

If I had background, I'd see about trying to use XML as a file system, but 
that may be more work than I want to take on. 

Anyone know of a small "bare bones" file system that will let me use SQL 
statements to return groups of records.... in Jython?

Thanks,

Al