Since I was recently going through my inventory of Javascript components to update a web site, I decided to link a few of the nicer ones here. They are not as integrated as the GWT or Microsoft Atlas, but - at times - still quite useful:

Tigra Menu

http://www.softcomplex.com/products/tigra_menu/

This is a nice, easy to configure JavaScript menu bar that works quite well across different browsers (with the notable exception of using absolute positioning, so IE and FireFox will *always* require some different handling).

There are a few more components ot SoftComplex - check also their 'Tigra Hints', 'Tigra Tree Menu', and some more of their components.

The basic edition is free - they have PRO components for money.

SynForce

http://www.netspinner.co.uk/synforce/html/synforce.html

This is a small validation library, that comes under LGPL.

Xin Calendar 2

http://www.yxscripts.com/xc2/index.html

Really nice JS calendar that is free, as long as you keep a link to yxscripts.com from your web site. REALLY nice and extremely configurable.