Request for a Database Backup plugin. Vote it up! ...if you find it useful.
It was mentioned to use sqldump or phpMyAdmin here: http://www.question2answer.org/qa/2358/best-method-to-import-export-the-database . But they aren't stright forward solutions, though. Especially for non-programmers.
My suggestion is to make it as simple as possible - two buttons in the widget admin section: export and import.