Local version of php/mysql site

Hi all, I've developed a web site where users complete a web form which pushes their data into a MySQL database. At the back end they can run reports of their input from this database. At the high end, users enter input into the form a few hundred times a day. Our site has about 99% uptime, but users have been asking for the development of a local version for them to use during the 1% downtime. Basically, I need to recreate the form so that upon submission is writes the data to a file on the users machine, which can then be uploaded to the site when it's back up. Does anyone have any resources that I could use to get started with this? Thanks, Zeth