TypeScript

TypeScript looks like a great improvement in large web app development.
http://www.typescriptlang.org/

Here is the definition file for Knockout:
https://github.com/borisyankov/DefinitelyTyped/blob/master/knockout/knockout-2.2.d.ts

Kill IE6 Bar

Do your users a favor:
http://www.ie6countdown.com/join-us.aspx