Ivo Wetzel covers some of the quirks of the JavaScript language. Some of these cause subtle bugs, some overturn conventional wisdom. It covers toString on numbers. Covers the advanced JavaScript features such as prototypal inheritance, this, closures, anonymous wrappers, type-casting, automatic semicolon insertion and hoisting of function and variable declarations.
Jim Ley covers the intricacies of type conversion, implicit and explicit. He covers type conversion into boolean, string, number, undefined, null; and parsing into floats and integers. This is backed up by conversion tables for quick reference. There's also a useful section on regular expressions for form field validation.