Cross Browser DHTML libraries

I've used DynAPI in the past: http://dynapi.sourceforge.net/

It's based on some work by Dan Steinman; it's pretty mature and has a nice object base - I was pretty suprised by the OO capabilities JavaScript offers.

There are lots of widgets available, as well: http://dynapi.sourceforge.net/dynapi/links.php?op=viewslink&sid=5

When you write websites, you are always looking at the same problems, like having your site working with different browsers.
.Net is good for the job from a server side perspective only.

I used different libraries for my client side scripts, and recently I found the solutions offered by Cross Browser very powerful and up to date.

Cross-Browser.com features two cross-browser DHTML Javascript libraries. They support IE, Gecko (NS6, Mozilla, Phoenix, Galeon, etc.), Opera, Konqueror, NN4, and any other browsers with similar object models. The CBE library implements the DOM object tree, the DOM2 event model, and other DOM2 interfaces. The X library is a small but powerful library developed as a result of my experiences in developing CBE. Both libraries use object-detection, instead of browser-detection, as much as possible. Extensive documentation and examples are provided on this site. A free download package is available which contains the libraries, examples, and documentation. CBE and X are distributed under the terms of the LGPL. Please read the license before using either of the libraries.