Parsley - The ultimate javascript form validation library
Heyoffline.js
Heyoffline.js is a simple tool that prevents your users from this kind of frustration. Written in CoffeeScript and compiled into JavaScript, the library can warn your users when their network goes down so that they don't lose anything. Once JavaScript is loaded, it can react to the loss of connection and change the page accordingly.
Get Your Form On: Modern Web Forms Tutorials
45 jQuery Plugins And Tutorials To Enhance Your Forms