We always design web applications but seldom think about it’s usability. Well, not exactly, we do care about usability, still we don’t have a reference for the standards to be followed by the developers/designers. But not anymore! Here comes the famous book called
Web Application Design Handbook – Best Practices for web-based Softwares.
Its a nice book and can be made a standard referance for following while developing web apps.
Have a look, its in PDF format.