I've written a small code snippet that adds 1Mb/100kB records into a
local SQL DB in order to test the DB's quota mechanisms :
See:
http://webkit.org/blog/126/webkit-does-html5-client-side-database-storage/
http://www.whatwg.org/specs/web-apps/current-work/#sql
http://www.w3.org/html/wg/html5/#sql
--Jorge.