There are a few jSQL plugins available in the /plugins directory on Github.
Data saved in the browser is usually only available to the application that saved it. jSQLEverywhere allows you to share your jSQL databases between different pages and apps.
jSQLMyAdmin is a debugging and development tool that creates an interface which allows you to run arbitrary jSQL queries on any page.
If your apps are making a lot of repetitive calls to a static webservice xhrCache can cache the calls and responses in a jSQL table to prevent unnecessary network requests.