Personally, I would use a remote XML file. Simply store it on your server and update it manually when you update your software. Have the software check the XML file periodically. Do not check for updates upon every page load as some individuals may not appreciate, although trivial, the bandwidth used upon each and every page load. Simply have it in the administrative area, for instance, and then only to individuals who have the ability to update the software -- if you have a hierarchy of administrators with differing permissions.

The good thing about XML is you can store lots of extra information in there. So you can have a version number, a download link, as well as a release log. The same goes for other similar storage formats, such as JSON.

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