This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
If this is a desktop app, then an embeddable DB like HSQLDB or Apache Derby might fit the bill. HSQLDB in particular stores its data in human-readable files, so a careful user could edit the DB by editing the file (provided the app doesn't use the DB at the same time).